There's a few that may fit (similar, not exactly as described):
Love Delivery
Happy Kuzo Life
Romantic Pornography
Gachiiki Chouhatsu Night
Omae ni Dakareru Nante Kittenai!
I know there is more, but I just didn't want to forget to put the ones I remember. Anyway, If I remember more, I let you know.
if it isn’t this you should definitely read it because it’s genuinely so good lol https://www.mangago.me/read-manga/migite_ni_miemasunoga_ore_no_kareshi_de_gozaimasu/
It is this one oOo thank you so much <3
I'm looking for a BL manga, where the protagonist had a girlfriend and he wanted to try anal (he asked her to do it to him), the girlfriend didn't want to do it so she broke up with him, and he ended up crying or drinking (I don't remember) and he tell the story to... a guy in a bar or his neighbor(?) and the guy is like "well I can do that for you" so they do it... and well I do remember they become a couple by the end.
So... anyone remembers?