https://vndb.org/v54519
https://www.getchu.com/soft.phtml?id=1317417&gc=gc
http://www.at-sakura.net/ntr/brand/127/index.html
https://dlsoft.dmm.co.jp/detail/aquras_0208/

Oh this might be interesting
A main couple who is FWB until a new man appears, 3 endings the one where MC loses her to the other guy , the one where he becomes an accepting cuck and the good one where he confesses he's jealous and doesn't want to share her with others and become a real couple despite her body has changed.

Base +24, sligy +14

The MC in this one is a massive hypocrite who has no idea how the FWB dynamic works, and just thinks it's the type of relationship he wants, when in reality, he wants to tie his 'Best Friend' down with exclusivity. Even if you opt for the committed cuck route, he's still not even sure he genuinely enjoys watching her with other men until the very end and the other guy just kinda gaslights him into believing he likes it.. The heroine pretty much always tries to make sure MC is comfortable with whatever they end up doing in the sharing scenario, and asks him if he is. Bro just ain't got much of a spine. smh

Base +6

@pr0dukt
Bro, the reason is because all his previous relationships ended in break ups and so was with the MH which is how both bonded and decided to start that FWB relationship.

Base +24