Straight top(?) x straight bottom, best friends to lovers, childhood friends, also hetero sex for a solid chunk of time (but it's with the guy who turns into a girl, within the main couple).
Official release on Renta, Coolmic and BookWalker, webtoon scroll version officials are here.
Series info:
https://www.mangaupdates.com/series/4e23p7x/kuro-gal-ni-natta-kara-shinyuu-to-yattemita
Confession: chapter 40, 43
1st: 3/25/23, 2nd: 7/6/23, 3rd: 11/21/23
Fucked by My Best Friend