I would hope that if any of them were to marry and have children, they would stop pursuing other women.

My guess is that they don't care one way or the other about what is important in a woman's life. They want to initiate an interaction that they hope will lead to a sexual encounter. They have no interest in what is important in her life.

It would be more accurate to say that they wish you would cater to their needs rather than saying they expect you to.

"... to get the approval of the other men who are with them when they do it."

Why are their peers impressed?

The motivations of "cat-callers" are complex and nuanced. If "cat-callers" are showing off for their peers, then they would only "cat-call" when their peers were present. Some may indeed be hoping to impress their peers, but why are their peers impressed?

Some "callers" may believe that a "cat-call" could lead to a sexual encounter. If the "caller" is successful even one time out of one hundred attempts, then he is likely to be encouraged to continue. Some may be desperate enough to try anything successful or not.

Sometimes a man encounters a woman who he finds extremely attractive. He may believe, rightly or wrongly, that he has no chance of even getting a date, let alone a sexual encounter with a woman who is that attractive. A "cat-call" could be the closest he believes he will ever come to an "intimate" encounter with her. Since a "cat-call" causes her some distress, it functions as a form of revenge against her for denying him the attention he longs for.

There are various motivations for "cat-calling."