In this answer, there is a statement which says that Krishna cohabited with Radha who is His aunt,
And this blog also says same.
So my question is, was Radha Krishna's aunt?
Goddess Radha's details are not found in Mahabharata, Śrīmad-Bhāgavatam (Bhāgavata Purāṇa) and Vishnu Purana etc. Though Brahmavaivarta Purana has detailed story about Goddess Radha and the answer to this question can be found in Brahmavaivarta Purana: Prakrti-Khandam: Chapter 49. Pronouncing of curse mutually by Radha and Sudama:
36 In the Varaha-kalpa, Radhika was born in the village of Gokula in the family of a Vaisya cowherd Vrsabhanu.
37 She was born without any human contact. Her mother Kalavati during pregnancy carried only the wind. At the time when the mother was giving birth to the wind, in the meantime Radhika appeared as her daughter.
38 After the expiry of twelve years, finding her becoming youthful, she was married to a trader named Rayana;
39 at the time of marriage only a shadow Radha was married to the trader while the real Radha herself disappeared.
40 After the expiry of fourteen years Krsna, the lord of the universe appeared there as an infant. He was brought to Gokula deceitfully because of the danger from Kamsa.
41 This Rayana was the real brother of Yasodha the mother of Krsna who happened to be an amsa of Krsna in Goloka and was his maternal uncle in the sacred forest of Vrndavana.
42 Brahma the creator of the universe had performed the marriage of Radha with Krsna.
43 Radha whose lotus-like feet were beyond the sight of cowherds even in dream, the same Radha enjoyed the lap of lord Krsna and her shadow was very much present in the house of Rayana.
46 In the sacred forest of Vrndavana in the land of Bharata, Krsna the lord of the cowherds enjoyed the company of Radha in Vrndavana for a short duration.
47 Thereafter because of the curse of Sudama both of them were separated from each other.
So this chapter clearly states that Radha was elder to Krishna and was already married to Yashoda's brother Raayana before Krishna's arrival in Gokula which makes Radha as maternal aunt (Maami) of Krishna. But it says only shadow Radha was married to Yashoda's brother Raayana.