Help please

All I remember is a scene they were out eating and were eating outside. Then a woman then comes up to them and starts talking about how she’s the ex-fiancé of the male lead. And I remember that she tells him that she’s getting married. He tells her good for you and other polite stuff and she says something along the lines of you’re still so polite and the interaction ends. Main character gets jealous but Male lead reassures him that his relationship happened before he recovered his memories and wasn’t really in love with any of the people he used to date. I don’t recall what would have made him lose his memories or if it was some sort of reincarnation trope which is why I would like to reread it. If you have any idea please let me know, it’s also possible that instead of the male lead fiancé it was the main character’s but I’m more sure it was the male leads.