How to not feel so insecure in a relationship?

This relationship that i am in, i know this dude has a serious wandering eye. It bugs the heck out of me cause i know im not the only girl he wants to look at *which is any girl's wish (to have him want to look at you and only you)*.
I havent really ever been in a relationship where i feel so insecure before, the guy never really had a wandering eye and really did just want to look at me, with a glance here and there at a celeb.
How do i blow this off? how do i learn to not feel so insecure and not good enough?
can anyone relate? should i take this as a sign this hes not good enough for me, if im feeling to terribly insecure? Tweet