
There’s a story where this guy has cancer or something, and his boyfriend cheats on him or something (no I’m not talking about the 10 years one)

It might be this(?): https://www.mangago.zone/read-manga/ways_of_parting/
The mc doesn't have cancer but he stays in a coma for years and when he wakes up he finds out his boyfriend 'cheated' (not really, he thought he was dead) and got with somebody else

It’s a story of some guy with a ghost/spirit in his room. The ghost/spirit is another guy, and at the end of the story the ghost disappears and it’s super sad or something idk (I honestly don’t remember)

U didn't mention whether it's a bl or not but if it is then it might be https://www.mangago.zone/read-manga/lonely_to_organdy/

Not really sure but is it https://www.mangago.zone/read-manga/one_room_angel/ ?
Its similar to "One room Angel" by Harada, It's a bl (?) where some spirit or something appears in this guys room and by the end of the story he disappears and the MC if left alone. I need to know the name of it
It´s like and old bl manga?? About a painter?? i REMEMBER ITTTTT AAAAAAAA
https://www.mangago.zone/read-manga/kabe_no_naka_no_tenshi/
maybe its this one
https://www.mangago.zone/read-manga/dos_obake_ga_nekasetekurenai/ This? I think it has similar vibe to harada, he left but they meet in the end and he can control his spirit form.
Maybe one of these?
https://www.mangago.zone/read-manga/asagao_wa_yoru_kara_saku/ https://www.mangago.zone/read-manga/toumei_na_ai_no_utsuwa/