Wait, hit the brakes. You're talking as though these individual guys have fathered the kids of the single moms. It's likely that the ones you're referring to aren't them. Look at it from this perspective, maybe the guy knows he's not ready for the responsibility of being financially or mentally responsible enough for a kid also, and isn't looking to jump in a relationship that starts with a kid present. It's not fair to the kid either.

here is a crazy take. Let people date who ever they want. stop getting your feelings hurt because your ego can't handle reality.