Hello. Opinions needed

I am in a conflict with my soon to be ex partner. This is because of his wandering eyes. His thinking is, "its normal" and "all dudes do it". To me this was icing on the cake. Just fed up with that mentality. I for one know this is not true that all men look. My girlfriends boyfriend do not, I ask and observed personally. Also I observe many couples in public and see the two walking side by aide totally in tune with eachother. He's wrong for saying this.

I would like to know if you think this is true for all men? Also what drives a man to stare at other women while in public with his own girlfriend/spouse, etc...

And lastly, would you say if one did this in a relationship that they are ultimately not the one for the other?

please help