@BeExcellent you are usually good with your posts and comments and I usually agree with them but I have to disagree with you on this and agree with OP on this. I don't think OP is insecure.
First if a girl is attractive she is going to get a lot of looks and attraction which is normal and the guy better be secure with himself to deal with this or he should be dating a whale. Also the girl better be rejecting those advances if she is in a relationship out of respect.
OPs post basically stated that if the guy is in a relationship with a girl and the girl is eye f'ing other guys that's a red flag and is a sign of disrespect which I agree. Clearly the girl is going to find other guys attractive which is normal but there is a difference between glancing at a guy and eye f'ing a guy with desire (
@BeExcellent you know the difference especially if you are attractive).
I get these kinds of looks of desire from girls myself when they are with their bfs and husbands and I find it disrespectful to their significant other. My thinking when this happens to me is man she must have settled for that guy because a girl that did not settle and who had desire for the guy she is with will not look at another guy like that.
I have friends wives who look at their husband with that desire but do not look at me with that desire even though they have told me that I am handsome because she respects her husband and knows how to control herself.
Summary for the guys: If a girl you are with is eye f'ing other dudes she does not desire and respect you. Move on and find a girl that does.