Krishna cannot repay for the Gopi's love

SB 10.32.22

na pāraye 'haḿ niravadya-saḿyujāḿ

sva-sādhu-kṛtyaḿ vibudhāyuṣāpi vaḥ

yā mābhajan durjara-geha-śṛńkhalāḥ

saḿvṛścya tad vaḥ pratiyātu sādhunā

I am not able to repay My debt for your spotless service, even within a lifetime of Brahmā. Your connection with Me is beyond reproach. You have worshiped Me, cutting off all domestic ties, which are difficult to break. Therefore please let your own glorious deeds be your compensation.

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"

Gopis: To see Krsna is the goal of all persons

Purport from SB 10.21.7

The gopīs were aware that their mothers or other elder persons might hear their romantic words and disapprove, and thus they said,akṣaṇvatāḿ phalam: "To see Kṛṣṇa is the goal for all persons and not simply ourselves." In other words, the gopīs indicated that since Kṛṣṇa is the supreme object of love for everyone, why couldn't they also love Him in spiritual ecstasy?

Those fixed in devotion do not have material desires

SB 10.22.26: The desire of those who fix their minds on Me does not lead to material desire for sense gratification, just as barleycorns burned by the sun and then cooked can no longer grow into new sprouts.

The words mayy āveśita-dhiyām are very significant here. Unless one has achieved an advanced degree of devotion, one cannot fix the mind and intelligence on Kṛṣṇa, since Kṛṣṇa is pure spiritual existence. Self-realization is a state not of desirelessness but rather of purified desire, wherein one desires only the pleasure of Lord Kṛṣṇa. The gopīs were certainly attracted to Kṛṣṇa in a mood of conjugal love, and yet, having fixed their minds and indeed their entire existence completely on Kṛṣṇa, their conjugal desire could never manifest as material lust; rather, it became the most exalted form of love of Godhead ever seen within the universe.