Most Helpful Guy
I think it's more individual rather than gender based. For instance, I could forgive cheating, but my mentality is eye for an eye. So I'd expect to be able to cheat straight back. Others guys can forgive cheating without any negative feelings. Others would leave immediately2
Most Helpful Girl
I think it's because we are more emotionally weak; by that I mean it's hard to just let go even if they hurt us; especially if the relationship has moved on from emotional physical.
But it's better to not stay with a cheater; because trust and loyalty is broken. You can forgive them perhaps but not stay together.2