Is the choice of our spouse predestined by karma (are marriages made in “heaven”)? Is it predestined by God? Does my free-will have a role in such a choice?
If I like one person and am neutral towards another, how do I make a decision that is best? Should I simply surrender to God and let God decide - is such surrender cowardice or escapism? If God will make a decision, how does God decide in such situations - will God take my preferences into account?
At every step, freewill has a bearing upon one’s destiny. The range of choices in various situations of life, including marriage, is defined by Karma - both past and present (i.e. actions and choices made in past and present life), and yet there is scope for redefining those choices by our present actions.
Krishna does not directly involve Himself in arranging the details of karmic events in everyone’s life. As stated in the Gita (BG 9.9, BG 13.23) — including those who want material enjoyment — He is seated in their heart as though neutral, witnessing and permitting the soul’s material enjoyment as well as sufferings that result from their own choices. Under His sanction, material nature awards the due results of their desires and actions, as they deserve.
But for those who want to become His surrendered devotee, Krishna personally orchestrates their life and guides their decisions in such a way that will bring them closer to Him. (Bg 10.10) Thus, He may bless His devotee with a marriage situation which will be conducive to spiritual progress.
In short, the Lord’s reciprocation in guiding our life depends on our predisposition or inner purpose, and not necessarily the particular preferences and choices.
Regarding making the decision on who to marry, certainly it is nice to be surrendered to the Lord’s direction, but surrender does not dictate absolute passivity. While sincerely praying for the Lord’s guidance and inspiration, you can at the same time actively make considerations based on your personal nature, compatibility and needs. In the same spirit, you should also seek counsel from experienced grihasthas who know your nature well, and who can take your attention beyond superficial attractions and aversions to help make a wise decision.