CC Madhya 8.81
“ ‘Suddenly, due to their feelings of separation, Lord Kṛṣṇa appeared among the gopīs dressed in yellow garments and wearing a flower garland. His lotus face was smiling, and He was directly attracting the mind of Cupid.’
This verse is from Śrīmad-Bhāgavatam (10.32.2). When the rāsa dance was going on, Kṛṣṇa suddenly disappeared, and the gopīs became so overwhelmed, due to His separation and their intense love for Him, that Kṛṣṇa was obliged to appear again.