There is a yaoi/shounen ai Manga (may be a one-shot in a book of another series) that I have been trying to find for ages.

A boy who's parents are very conservative and his boyfriend get married (? Or engagaed) to each girl within a lesbian couple. I remember the boyfriend being upset by it and one of the lesbians has dark hair and was funny in her standoff/blunt way.

Any ideas? Trying to find this manga has kept me up so many nights.

There’s a couple with same premise but the last story of Furachi na Bokura fits best.
Others are:
Two weddings and a funeral
Wedding bells are ringing

That's it! I had a feeling it might be something by Fuwa Shinrrinbut I couldn't pin it down