I’m not 100% sure if I should put this post here with 18+ but it does contain cheating and a lil bit of sex I think.
I don’t think I ever finished reading the manga but this is what I can remember! The story first takes place in middle school I believe. She talks about how she really wants a boyfriend so she can experience love. In their home room they have to change seats. Where she ends up sitting in front of the love interest. Everyday they get closer and closer together so the FL confesses her feelings. Our ML accepts her feelings but tells her to wait for him as he has some debts to settle. After a while of not seeing the ML she feels uneasy. However he comes back for her carrying her to the back of the school and kissing her. I think the setting does transition into high school. Where the ML cheats on her with the female manager of his team. They end up going on a vacation afterwards and making up. She even makes love to him in the same room where he did it with the manager. The FL ends up following him to a reunion where his ex-girlfriend will be. The reunion is at a karaoke room where she watches from a room across. He eventually sees her and joins her in the room that she rented for an hour or so. They kind of make up and laugh abt it from what I can remember.