Why is a need for fidelity insecure and clingy?

I wouldn't say that I've been clingy in any of my last three serious relationships. I'm the opposite. I wouldn't even classify myself as insecure. Yet, there's a definite line in the sand that I need drawn.

It's bothering him for a reason. What are those reasons, other than tearing him down. He might need to walk if she's not on the same page, I agree.

You know what? I might even be so bold to classify his girlfriend as the insecure one. Searching, Searching, Searching for that void to be filled by needing numerous extras in her life...sayin'