What in the peak gooner down bad manga is this gang
Anyways, I think is this one
Pretty sure it got an anime too
https://www.mangago.me/read-manga/world_s_end_harem_after_world/
Maybe Desuraba 1 or 2? They both have the same concept
https://www.mangago.me/read-manga/desuraba/
https://www.mangago.me/read-manga/destiny_lovers_2/

Looking for an ecchi manga that I believe took place in an apocalyptic world where I think 99% of males died off from some disease so it’s women dominated. Mc is a chaste male w/ a gf or situationship (idr) and at some point they get separated and rogue women find him and want to rape him to get impregnated.