It's been a very long time since I had an EX.  I've been married 22 years now.  Do you know much about those relationships.
I know the term can sometimes have a derogatroy meaning, bringing up unrequited feelings
Yes, I can see how that would happen.  I think many people may have issues due to past relationships.
Ex can mean a few different things besides an former romantic partner.  Such as ex friend or ex co-worker