Trying to find stories with regret

Im trying to find stories where someone regrets something they did (ex. taking their partner for granted or cheating) i want it to make my heart ache they do not have to end up together, one of them can die, idc as long as one ends up regretting and feels so hurt. stories I’ve read and am looking for some alike are 10 years I loved you the most, Jinx (the most recent chapters), Life Senjou no Bokura, Marry My Husband, Dominated by the Powerful Top, Run Away, Assistant Manager Ha!, BJ Alex, No Love Zone, Struggle, A Painter Behind the Curtain, & Unreachable. Ik there’s more that I’ve read I just can’t remember the names but I want stuff like that where the regret is the main point of the story and it is like the most important part, the climax.