You have a lot of anger/frustration/hurt going on here. It might be worth considering that potential matches are picking up on this and it's spooking them off. Coming across as angry and/or desperate will only hurt your cause.
Perhaps you might try having a trusted friend/partner/metamour proof any messages you're sending if you're dating online.
All that said, it sounds like you have some self work to do while waiting for the right (additional) person. It's not a contest, you're not a fifth wheel, and you need to be happy with yourself, partnered or not, before bringing someone else into a relationship. Don't define yourself by your relationships.