The devotees of the Lord are always in the heart of the Lord, and the Lord is always in the hearts of the devotees. That is the sweet relation between the Lord and His devotees. Due to unalloyed love and devotion for the Lord, the devotees always see Him within themselves, and the Lord also, although He has nothing to do and nothing to aspire to, is always busy in attending to the welfare of His devotees.
(Srimad Bhagavatam-------1:9:47------purport).

The sum total of devotional qualities is development of unalloyed love for Kṛṣṇa. This unalloyed love for Kṛṣṇa can be achieved simply by hearing about Kṛṣṇa. Lord Caitanya accepted this principle—that if one in any position submissively hears the transcendental message spoken by Kṛṣṇa or about Kṛṣṇa, then gradually he develops the quality of unalloyed love, and by that love only he can conquer the unconquerable.
(Srimad Bhagavatam-------4:12:42------purport).

"O son of Mahārāja Nanda (Kṛṣṇa), I am Your eternal servitor, yet somehow or other I have fallen into the ocean of birth and death. Please pick Me up from the ocean of death and place Me as one of the atoms at Your lotus feet." In another prayer Lord Caitanya says, mama janmani janmanīśvare bhavatād bhaktir ahaitukī tvayi: (Cc. Antya 20.29, Śikṣāṣṭaka 4) "Life after life, kindly let Me have unalloyed love and devotion at Your Lordship's lotus feet."
(Srimad Bhagavatam-------5:18:9------purport).

The whole spiritual process is technically called yoga, or linking with the Supreme. It is something like a long staircase, and the upward steps are variously designated as regulated work, transcendental knowledge, mystic powers, and ultimately bhakti-yoga, or devotional service. Bhakti-yoga is pure and unalloyed, being entirely beyond all the preliminary steps. Such unalloyed devotional service in favor of the Supreme Lord was displayed at Vṛndāvana when the Lord descended there, and thus the yoga exhibited by the gopīs of Vṛndāvana is the highest unalloyed love of Godhead, the perfection of bhakti-yoga. To rise to the stage of love shown by the gopīs is very difficult, but this stage is attainable for serious conditioned souls.
(Light of the Bhagavata).

Without love of Godhead there is no meaning even to direct contact. During the presence of the Lord there were thousands and thousands of men, but because they were not in love of Godhead they could hardly realize the Personality of Godhead, Śrī Kṛṣṇa. Therefore we must first activate our dormant love of Godhead by following the prescribed rules and by following in the footsteps of the authorities who are actually fixed in love of Godhead. The gopīs provide the highest example of such unalloyed love of Godhead, and Lord Caitanya at the ultimate stage of realization displayed the viraha worship in the mood of the gopīs.
(Light of the Bhagavata).

Love for Lord Kṛṣṇa is very pure, just like the waters of the Ganges. That love is an ocean of nectar. That pure attachment to Kṛṣṇa does not conceal any spot, which would appear just like a spot of ink on a white cloth.
Unalloyed love of Kṛṣṇa is just like a big sheet of white cloth. Absence of attachment is compared to a black spot on that white cloth. Just as the black spot is prominent, so the absence of love of Godhead is prominent on the platform of pure love of Godhead.
(Sri Caitanya Caritamrta------2:2:48------translation and purport).

"Unalloyed love of Kṛṣṇa is like an ocean of happiness. If someone gets one drop of it, the whole world can drown in that drop. It is not befitting to express such love of Godhead, yet a madman must speak. But even though he speaks, no one believes him."
(Sri Caitanya Caritamrta------2:2:49------translation).

By hearing the talks between Rāmānanda Rāya and Śrī Caitanya Mahāprabhu, one becomes enlightened with the transcendental knowledge of the mellows of Rādhā and Kṛṣṇa's pastimes. Thus one can develop unalloyed love for the lotus feet of Rādhā and Kṛṣṇa.
(Sri Caitanya Caritamrta------2:8:307------translation).

The unalloyed love of the gopīs and Śrīmatī Rādhārāṇī is without any trace of material lust. The criterion of such transcendental love is that its only purpose is to satisfy Kṛṣṇa.
(Sri Caitanya Caritamrta------3:7:39------translation).

When all misgivings and personal deficiencies are removed, there is a standard faith in transcendental matter, and the taste for it increases in greater proportion. This stage leads to attraction, and after this there is bhāva, or the prior stage ofunalloyed love for God. All the above different stages are but different stages of development of transcendental love. Being so surcharged with transcendental love, there comes a strong feeling of separation which leads to eight different kinds of ecstasies. Tears from the eyes of a devotee is an automatic reaction, and because Śrī Nārada Muni in his previous birth attained that stage very quickly after his departure from home, it was quite possible for him to perceive the actual presence of the Lord, which he tangibly experienced by his developed spiritual senses without material tinge.
(Srimad Bhagavatam-------1:6:16------purport).