Likely most Chinese speaking countries
When a man is cheating on a woman, the woman may choose to stay in the relationship, and may also choose to leave.
Sometimes when they choose to leave, they will tell others they choose to leave to 成全他们 (Chéng Quán Tā Mēn, literally: help them), as in: they seems to be a perfect match, I will step aside and help them to be the perfect couple.
This is sort like the "acceptance" stage of grief. But depending on the perspective this can also be interpreted as self-moved: you didn't do anything much but thought your act was noble.
A: I heard your boyfriend was cheating on you.
B: Yes we broke up, I helped them.