The reason why Krishna does not immediately reciprocate
From VCT Sarartha Darsini Tenth canto commentaries: Purport to Text 10.32.20:But the reason I do not immediately reciprocate the affection of living beings even when they worship Me, O gopīs, is that I want to intensify their loving devotion. They then become like a poor man who has gained some wealth and then lost it, and who thus becomes so anxious about it that he can think of nothing else. Srila VCT writes: Krsna says: For those surrendered souls who worship Me through nama-kirtana and other means, I do not respond in order to make their worship more perfect. O Gopis(abala-gana) who cannot understand My real intention.! Not seeing Me, those surrendered souls develop deep humility, feeling, 'Alas, alas, everything I have done has been useless. Because I am offender, Krsna has not shown even the slightest favor toward me. Let me be damned!" "By constantly thinking in this way, those who have not yet developed mature love for Me will become free from lust and anger and awaken pure devotion full of power and brilliance. However, the nature of those who already have nature love(krsna-prema) for Me is different. For them, I do not respond in order to increase their attachment to Me. I appear and then disappear, in order to deepen their loving attachment." "In this way I am actually merciful. It is desirable for My worshipers to have this complete attachment to Me. Thus to increase that attachment more and more, I, even though externally failing to reciprocate very much with them." "Although you gopis are the ideal examples of those who worship even those who do not worship them, I too am actually very merciful, as muh as you are, since I have given you the gift of my darsana. One should not think that only if I am present that I respond, and if I am absent I do not respond. For then my promise ye yatha mam prapadyante tams tathaiva bhajamy aham, 'I will respond accordingly as they worship Me'(BG 4.11) would be broken"