Tricky question and therein lies the superiority of the Radha-snehadhika sakhis over others. Srila Kunjabihari Das babaji Maharaj explains this nicely in Manjari swarupa nirupana as follows:
In the ananda-candrika commentary on Ujjvala-nilamani 2.15, Visvanatha writes that although all sakhis find their own happiness by arranging for the pleasure of the nayika in union with her Lord, still a general division can be made of two categories from amongst them. They are :
(1) those whose bodies are extremely attractive to Krsna due to their having salient qualities of love, beauty and coquettishness, etc.
(2) others who are somewhat inferior in these respects and so are not so attractive to the Lord’s romantic aspirations.
Thus, girls of the former category may occasionally, at the behest of their friend and mistress (yuthesvari), desire for erotic dalliance with Krsna, for his pleasure. These sakhis include Lalita and the other parama-prestha-sakhis. The second category of sakhi, however, never entertain such aspirations. They are Kasturi and the other nityasakhis. (ananda-candrika to UN 2.15 (Kavya-mala edn., 46))
For an example, we can look to the Vrndavana-mahimamrta by Prabodha-nanda Sarasvati(VMA 16.94):
One day one of srimati Radharani’s handmaidens whose exclusive desire is to relish the flavour of serving her lotus feet and who never thinks for a moment, not even in dreams, that she would have any kind of intercourse with Krsna, was accosted by him who shocked her by tearing away at her blouse and uncovering her bosom. She started crying, “No, no, what are you doing?” while srimati Radharani, my very life and soul, stood by and watched, laughing.
The nitya-sakhis have a certain reward for their unique spirit of abnegation, something which is withheld even from Radharani’s dearest comrades like Lalita and Visakha. That reward is described for us by Raghunatha Dasa Gosvamin in Vraja-vilasa-stava(Verse 38):
I take shelter of the handmaidens of the Queen of Vrindavan,
who are led by sri Rupa Manjari
and who lovingly satisfy her
by offering hazelnuts and other condiments,
massaging her feet, bringing fragrant water
and arranging trysts with her gallant
and have thus become most dear to her.
They are thus allowed to enter the scene
of the Divine Couple’s most intimate affairs
without the slightest discomfiture
a reward not given even to her dearest friends.
This is the area where the manjaris are unique and distinctive. Ranganamala and her friends, though they are themselves loving friends, either on their own initiative or at the behest of Visakha and her friends, sometimes behave towards the
Ever-youthful Couple of Vraja just as if they were maidservants. Behaving shyly, they do this in order to obtain the highest ecstasy by listening to their extremely funny conversations as well as to gain their most cherished service.(Mukta-carita, p.111)
A further special feature of the nitya-sakhis or manjaris is that just as srimati Radharani and the other yuthesvaris are spontaneously and instinctively filled with an intense thirst to relish the flavour of Krsna’s form, taste, fragrance, touch and sound, so similarly the manjaris are spontaneously and instinctively attracted to both Radha’s and Krsna’s qualities. To what extent and how they are so attracted can be explained as follows. The nature of madhura-rasa is clear: the gopis want to please Krsna by offering their own bodies. Even Brahma prays to be able to drink again and again from the cup of his senses the honey-like nectar of Krsna’s lotus feet.(BhP 10.14.33) According to Caitanya-caritamrta, “the nectar of Krsna’s lotus feet” means his direct bodily contact.(Commentary on Brhad-Bhagavatamrta 1.7.99)
From this we can understand that the nayikas serve Krsna by directly relinquishing their bodies to him that is their qualification for being in the madhura rasa. The manjaris, on the other hand, are unenthusiastic about such type of service. They never contemplate such a possibility, even in their dreams.
Yet, the question may be asked, if there is no possibility of madhura rasa or romance without physical intimacy, how can the platonic spirit of the manjaris be graced with the name of samartha rati or kama-rupa bhakti?
In answer to this question, it should be said that the object of the manjaris affection is the Holy Couple of Sri Sri Radha and Krsna together. Therefore, the perfection of the manjari’s power of sight and the thirst of their eyes is to see that couple locked in embrace. The craving of their ears is to hear the Holy Couple’s sweet murmuring conversations and that is the fulfillment of their sense of hearing. The desire of their tongues is to relish the flavour of the condiments touched by the Holy Couple’s lips, and in that way their sense of taste attains perfection. Similarly, the sweet fragrance that arises at the Holy Couple?s union is the object craved for by their nostrils and its experience is the fulfillment of their sense of smell. The tactile sense finds plenitude in massaging the Holy Couple’s feet and bodies, and this is the only object of their sense of touch.
In this way, it may be said that of the four types of sambhoga (sexual union) mentioned by Jiva Gosvamin (i.e., by sight, conversation, touch and copulation) the first three are present in the manjaris to some extent. The question is, how do they experience samprayoga, or intercourse? We get some light on this point from the following passage from the Govinda-lilamrta:
Just as the moon enlivens the lilies, so Krsna is the bright moon who enlivens the lily-like hearts of the residents of Vrindavan. His pleasure-giving potency is personified in Radha, who is like a creeper whose fruits are prema. Her girlfriends are like the unlimited branches, leaves and flowers which expand out from her self and are thus equal to her. For this reason, when that winding creeper of love is watered with the heavenly potion of Krsna’s sporting activities, then the leaves and flowers (the sakhis) find hundreds of times more pleasure than if they were themselves to be sprinkled this seems quite normal.(GLA 10.16, quoted in Caitanya-caritamrta, 2.8.211)
Prabodhananda Sarasvati also states in the Vrndavana-mahimamrta(VMA 1.54):
The pleasure felt by the eyes of the sakhi alone in seeing Radha merged in the ocean of love for Krsna makes all the Supreme Lord’s festive arrangements for his own happiness seem insignificant.
Another quote from the Govinda-lilamrta (11.137) of Krsnadasa Kaviraja illustrates the power of the vicarious pleasure of the manjaris:
If Krsna should touch srimati Radharani,then lo and behold! her sakhis start to tremble they sweat and their body hairs stand on endand tears well in their eyes. And if Krsna should carefully sip the spirituous liquor of Radha’s lips, it is they who become intoxicated! This is truly something wonderful.
In his commentary on this verse, Vrndavana Cakravartin observes that this verse contains the rhetorical embellishment (alamkara) known as asangati or non sequitur. Asangati is defined as arising when causes are described as being inflicted on one entity have their effects reproduced in a completely distinct one. Here, the Lord is touching and kissing Radha, but the effects of trembling and intoxication are described taking place in the bodies of the sakhis.
Another verse can be quoted here from the ahnika-kaumudi of Kavi Karnapura where Krsna says:
O doe-eyed beauties!
When your girlfriends are absent,
you may have to look at a mirror
before you can say whether you are happy or sad.
They reflect every mood of yours
they perform all the services of a looking glass!
When tears fall from your eyes they also cry;
when you are excited, their hairs stand on end;
when you laugh they also do so;
and when you become depressed,
they also look down-hearted.(AK 5.128)
In the Krsna-bhavanamrta, there is another verse which illustrates the point:
Radha’s handmaids are unable to maintain their lives if they cannot see the pastimes of the beautiful Divine Couple; with great eagerness they had gathered about the window of the forest cottage in which Radha and Krsna were locked in embrace and one of them said, Friends, what an amazing and wonderful situation is this they have gotten themselves into.(KBhA 20.26)
If the sakhis can feel intoxicated when Krsna kisses Radharani, then it is not altogether surprising if they get an even greater pleasure by watching the intimate activities of the Lord and his mistress than they would from their own. The reason for this is that they are not lovers in the mundane sense, but are supreme, the transcendental Lord and his celestial mistress.
Not only are Radha and Krsna transcendental, but so also are the sakhis . In the Krsna-bhavanamrta they are described in the following way:
These handmaidens of Radharani are unexcelled in this universe for their beauty is without bounds. The rays coming from the nails of their toes defeats the glory of the lightning bolt. Each one of them is an incarnation of Radharani’s expertise in loving dalliance and thus competent to herself become a competitor for Krsna’s affections. Yet such desires do not enter their minds for even a moment because they are completely desireless. In this way, they are eligible to eternally dive into the ambrosial sea of service to her.(KBhA 2.1)
Without bhava or feeling, the ecstasies of sacred rapture cannot be experienced. Without feeling, the ecstasies of love cannot be appreciated. To relish Krsna’s sweetness, one must become similar to him in quality, otherwise it will not be possible. Just as Radharani’s competent affection is not separable from her identity, eternal and self-manifest, so too the sakhis and manjaris have love for the Divine Couple which is similarly uncaused, self manifest and directly produced from their own identities. This is beyond normal experience and thus inconceivable. “Those things which are inconceivable are not accessible by mental speculation“.(MBh cited at BRS 2.5.93)
The actions of the Lord are supra-mundane, its ways and means are all transcendental; thus the unfortunate hear about them and even so develop no faith in him.
Sometimes Radharani makes arrangements for the manjaris to meet Krsna to be enjoyed by him; but even this intercession on her part does not shake their indifference to such direct erotic union with the Lord. srila Rupa Gosvamin gives an example in the Ujjvala-nilamani, which Visvanatha expands upon as follows in his commentary to UN 8.89:
One day, srimati Radharani arranged through another of her friends for Mani Manjari to have a rendez-vous with the Lord in some forest glen. That friend, after trying persuasively to convince the reluctant manjari finally returned to Srimati’s side in failure. She then said to her, Dear friend, you told me to try and I did. I went to Mani Manjari and tried to tempt her in many ways. I said,My friend, I don’t believe there is any thrill in this entire universe that can compare with the ecstasy of Krsna’s embrace; you really should try it one time. Lalita and the other sakhis sometimes have trysts with him, why shouldn’t you, just this once? They can act as both friends and, occasionally, independently as Krsna’s mistresses too. There’s nothing wrong with it, why don’t you be like that too? Otherwise, you become too insignificant!
Radhe, after hearing these arguments of mine, Mani answered me by saying,“Friend, when Radharani enjoys the pleasure of Krsna’s company, then I find the happiness I feel is greater than that which I could gain by doing anything for myself at all.” Therefore, dear Radhe, I am completely convinced that her heart is entirely pure because despite all temptations and clever tricks on my part, she showed not the slightest urge for going for a meeting with Krsna.
Sometimes Krsna also personally tries to seduce the manjaris and meets with similar failure( Vishwanath’s commentary on UN 8.88).
One day one of Radharani’s girlfriends was picking flowers for the purpose of making a garland. Sri Krsna chanced upon her at that time and immediately proposed to her, O beautiful one, why not perfect your life by passing a few moments with me in this forest grove’ as well as saying many other sweet and enticing words. The bewildered girl put aside all her feminine tactics and arguments and very simply said to the Lord,
Govinda, I have only one desire:
to have the ever-greater intelligence
to be able to serve you and Radha
on the field of your ever-expanding, ecstatic romance
so that you experience newer and newer bliss;
for by such service, unlimited gopis have attained
the very limit of the fulfillment of their desires.
Therefore, oh Lord of Gokula, my mind
never becomes eager for your direct embrace;
it does not crave for such enjoyments,
please just engage me in that service.
Direct erotic union with the Lord is thought by many to be the ultimate object of the fulfillment of the gopi’s desires but the manjaris have no attraction for it. Visvanatha glosses the above-quoted gopis’ words: “Secretly watching your activities with Radharani in the forest groves seems to me to be hundreds of times more rapturous than direct intercourse with you.”
When a higher happiness can be found in other ways, then what intelligent person will take up inferior ways of pleasure-seeking?
The direct act of love-making functions as a climax to the variegated sportings of the transcendental loving pair and is not prominent as their highest source of happiness. As Rupa Gosvamin describes it at the very end of Ujjvala-nilamani (15.253): Those who are knowledgeable about sacred rapture have experienced that the actual sexual act is not as great a cause of happiness for experienced lovers as their various flirtations and loving exchanges.
Furthermore, the sexual act of the Supreme Lord has no tinge of mundaneness to it whatsoever. One should bear these points in mind at all times while going through this or any other book on the supramundane love life of the Lord