gosh, many men are that way. Particularly I find when men are in their midlife crisis, they would do those nonsense things. Why?, to feel young, to escape the reality of being mature (I would avoid the word old as I believe 50ish is not old in my book). Remember when he looks at them, he probably thinks of himself when he was young, strong and would imagine those girls are head over heel for him.
I do not have this problem with my husband. But my cousin (male cousin) is the worse on this. He is in his 60ish, and he went to cafe bar where the waitresses wear hardly anything (see through shirts and pants, ...yes, believe me) and they are in there 20ish. Can you believe that?
I tell you another story, my ex-fiance when we were in our 20ish, he loved me dearly he said so all the time and I believe him till this date. Yet, he opened zillion social network accounts, collected zillion girls pictures, store dozen of girls cell numbers, chatted with them and even met them in person behind my back. When I caught him, he could not explain and kept running around my questions, giving me all BS lame answers and even tried to blame me as my head is not "clean" and that he did all those things but it mean nothing. Of course we broke off. After we broke off, he got him self drunk to near death, lost his job and kept IM me every 2, 3 months wanting me back. he Kept saying he is emptied inside, and dead inside without me and had been praying for me to come back. Can you understand this behavior?, I could not and I still can't. He loved me, but why did all that risking the love of his life? I think some men need to do such things to prove his power and that he is wanted and loved by women (one is not enough) even tho I was the only one he really loved and cared for.
I think there is some defect in some of these men's gene...He struggled with his life for 2 years after the breaking up... I left and never wanted to look back... I was so painful for a year and finally moved on.