Not really as far as I know! It's not uncommon to have a poly person dating or even married to a monogamous person. Knowing that you have the capacity to love more than one person doesn't mean that you necessarily WANT to be in a relationship with more than one partner. I think most poly folk will admit there are times that it makes sense to focus on one or just a few relationships.
Either way you are not alone and it's a fallacy to say that poly folk are "stuck" in monogamous relationships or that they MUST cheat. My partner has for most of our 5 year+ relationship identified himself as a monogamous person in love with a polyamorous person. He know I do not cheat and also knows that if he desires to begin a relationship with someone else he will be supported and loved.