Does it really bother guys when other men look at their girlfriends?

I had no idea a dude was checking me out when my guy were out and about. My guy all of a sudden walked behind me real close, and was like that until we got to his car. I was like...what's up? He said that he noticed a dude staring at my a$$ so he needed to block his view. So yeah, guys don't like it when other dudes stare at their girl in their presence.