Welcome to our forum.
Sorry to hear you have had some bad luck in finding poly relationships. Mono/poly relationships can work, but the monogamous person has to at least be poly-friendly.
I hope better luck will come your way in the future. Meantime if there's anything we can do to help, let us know. Lots of good/informative threads to read here, have a look around and see what calls to you.
Love means never having to say, "Put down that meat cleaver!"