I agree with you, if you really are in love with someone you don't cheat. It's not even an issue- you just dont ever want to or even think about it. But in a situation where you're on holiday, you might be looking at it from a perspective of a special experience. Of all the times that I've THOUGHT I was in love, there's only been once where I felt the natural desire to be faithful. Maybe your friend just THINKS she loves her boyfriend, cares about him a lot, ect. Is she going to tell him? I think that makes a difference too. Does she feel the guilt to tell him, ya know.