Counterpoint: I have an instinctive distrust of anybody who isn't good friends with at least one of their exes.

Are you going to tell me that you liked this person enough to date them but that in every single instance whatever caused you to stop being romantic also caused you to never want to talk to them again? Sounds like a red flag to me, dawg.

Dude's mom is entirely in the wrong here, mind you. In that situation I have been known to deliver a pointed "Mom, we are done, we are FRIENDS".