Hi
Isekai BL
Reincarnation, Transmigration
Reincarnated in Another World
Reincarnated in a Game World
Reincarnated in a Book World
Transported to Another World
Reincarnated Lover
Multiple Reincarnation
Reincarnated in the Past
Time Travel
Time Rewind
Part 2:https://www.mangago.me/home/mangalist/3123306/
When seme (or male lead if it's shoujo/josei manga) regretting all the bad thing he has done (especially to his significant other) and trying to make amend of his wrongdoings. Some of the list has uke that is very forgiving, never forgive or died. I don't mind whichever ending, it's just the feeling of regret, from doing bad things or taking things for granted.
Most in the list are yaoi/shounen-ai genre, that's why I used term 'seme'. Feel free to add if you have anything similar in mind.