CC Madhya 1.51
kṛṣṇera viraha-līlā prabhura antara
The last twelve years were simply devoted to relishing the pastimes of Kṛṣṇa in separation within the heart of the Lord.
Śrī Kṛṣṇa Caitanya Mahāprabhu enjoyed the position of the gopīs in separation from Kṛṣṇa. When Kṛṣṇa left the gopīs and went to Mathurā, the gopīs cried for Him the rest of their lives, feeling intense separation from Him. This ecstatic feeling of separation was specifically advocated by Lord Caitanya Mahāprabhu through His actual demonstrations.