When the gopis would see Krsna returning from taking the cows out to graze, they would gaze upon Him with greedy eyes and their ananda would increase. But when they couldn’t see Him, even a moment seemed like millions of yugas which would never pass. This is purva-raga, and countless beautiful sentiments are included within it.
The gopis felt that the time which elapsed during the blinking of their eyes was like an infinity, and they have themselves described this in the Bhagavatam (10.31.15):
atati yad bhavan ahni kananam
truti yugayate tvam apasyatam
kutila-kuntalam sri-mukham ca te
jada udiksatam paksma-krd drsam
When Krsna would spend the day wandering in the forest with the sakhas, the gopis, unable to see His beautiful face adorned with lovely locks of hair, would be anguished in separation from Him. And what to speak of that, even when Krsna was before them, they considered the tiny fraction of time which elapsed in the blinking of their eyes to be like millenniums, and they cursed the creator Brahma as being foolish for having created eyes which must blink. Our time is mostly spent joking around, but in comparison what kind of bhajana was performed by these great personalities?
Bhakti Rasayana, page 91 [CC-by-ND GVP]