Śrī Caitanya-caritāmṛta, Ādi-līlā 1.5
Sometimes Rādhā and Krishna are combined; sometimes They are separate. They are separate in Dvāpara-yuga, and in Kali-yuga they are combined as Śrī Krishna Chaitanya Mahāprabhu. Both are eternal expressions of the same Absolute Truth. Summer, autumn, winter, and spring continue in a cyclic order; it cannot be said that summer is the beginning and winter comes later. So, the pastimes of Śrī Rādhā and Krishna are eternally being enacted. In ancient times, sometimes Rādhā and Krishna divided Themselves and showed Their pastimes; again both of Them, the potency and the owner of the potency, are combined and closely embraced as Śrī Chaitanya Mahāprabhu. The predominating and the predominated moiety are mixed, and an extraordinary ecstatic feeling is there. Krishna is overpowered by His potency, and He Himself is searching after His own Self: kṛṣṇasya ātmānusandhāna. Krishna Himself is engaged in the search for Śrī Krishna, Reality the Beautiful. The influence of Rādhārāṇī over Krishna has transformed Him into a devotee, and He is searching Himself. Sweetness is tasting Itself and becoming mad. And it is living sweetness — not dead or static, but dynamic ecstasy, sweetness endowed with life. And He is tasting Himself, the personification of happiness, ecstasy, and beauty — and dancing in madness. And His performance of kīrtan means distributing that ecstasy to others. The ultimate sweetness, or ānanda, is such that no other thing exists that can taste itself and express its own happiness with such intensity.
~ Purport by Swami B.R Sridhar