Any bl where uke and seme are classmates and then it fast forwards to the future where the...

https://www.mangago.zone/read-manga/mr_miss/
https://www.mangago.zone/read-manga/warau_oni_ni_wa_fuku_kitaru/

This one is suuuper r*pey, but it has what you're looking for (not my cup of tea)
https://www.mangago.zone/read-manga/even_if_you_don_t_love_me/

https://www.mangago.zone/read-manga/doppleganger/

https://www.mangago.zone/read-manga/i_ll_be_here_for_you_19/

Contains r*pe
https://www.mangago.zone/read-manga/checkmate_1/

I wouldn't call his life "doomed", but he was indeed desperately in need of seme's help
https://www.mangago.zone/read-manga/guiding_hazard/

I'm not sure if it's your thing, but I quite like the story "make me bark". Basically, the uke finally gets a place of his own, but it burns down on the same day. He randomly thinks of a person from his school and decided to try asking him for a place to stay. The seme says yes and they start a cute cohabitation. I like it but it's a bit BDSM and dog play. All 100% consensual tho and the semes hot. ╮(￣▽￣)╭