Jitsu wa Watashi, Dekiai Saretemashita!?: Saitei Kareshi kara Saikyou Kareshi e

Satsuki has been dating her boyfriend Itsuki for three years. They now live together and are considering marriage, but it's far from smooth sailing. While she is struggling with that at home, one day Satsuki discovers at a company barbeque that Itsuki has been cheating on her with her coworker, Kana. When she freezes in the face of this discovery, her attractive and popular junior, Fujisaki, suddenly asks her out...! He's always kind and looking out for her. So, when he asked her out, it was just to lighten the mood when she was feeling down... or so she thought. But it seems like Fujisaki meant what he said. As Satsuki tries to figure out her feelings, Fujisaki continues to shower her with love. She's gone from controlling trash to adoring treasure?! (Source: MangaPlaza)