Most Helpful Guy
I wouldn't cheat on somebody because they're insecure. But not all guys are me
However I can understand a relationship ending because of it. In fact it's the reason one of mine ended.
If I am constantly around someone with no confidence. They think that they are not good enough. Constantly questioning everything I say or do. They don't trust you. etc. Their answer for everything I say or do is "you don't love me" or "I'm not good enough"
It becomes extremely draining on the guy. He tries to talk and reason with her. But a week later it's right back to the same old. Eventually the guy will start making excuses to not be around her. Which makes the situation worse. It just wears you out. Eventually for his own sanity he will leave.
Just to be clear either partner can be insecure. I used the female as the insecure one because that's what I can relate too. But the male can certainly be the one with the problem.