I think my partner is a Poly but he won't admit it
Hello, I am what some of you may call a hardwired mono. I have tried polyamory in the past, but I just know it's not for me. I have been dating a guy (I will use the name "Sam") for a couple of years now. We have a great relationship, get along very well, and have always been open and honest to each other about everything, until we ran into some communication issues recently.
Basically, Sam and I have been in a monogamous relationship for the past couple of years, except we sometimes have threesomes with other men or women. I guess you could call us "swingers."
A little while ago, Sam had sex with a girl (I will use the name "Molly") without my knowledge or consent. I didn't suspect this as Polyamory behavior at all initially, because a real Poly isn't dishonest nor have sex with people behind their partner's back. However, later on, he told me he cares a great deal about Molly and that she is special to him. Thus I suspected that he is probably interested in Polyamory, he just doesn't know much about it or how it works.
So I asked him if he was interested in a romantic relationship with Molly or any other women. He told me no, and said something along the lines of "I love you, and we are perfect together. I don't think I can feel the same way about anyone else." (I feel the same way about him) But I was confused. How could he care a lot about Molly, find her special, and sexually appealing, yet not want a relationship with her?
And, since then, he has been giving me more mixed messages. He bought the book "Ethical Slut" but doesn't actually intend on reading it. He also told me his fantasy is to live in a house with a bunch of girls. And whenever we are looking for a girl to join us in a casual threesome, he wants to "date" them first to make sure he likes them.
So, lately I tried to clarify my confusion and also to communicate more openly with him. But every time I bring up anything about Molly, Polyamory, or rules for our relationship to avoid future misunderstandings, he gets really angry and calls me jealous, which doesn't even make sense. How could I be jealous when I take pleasure in seeing him being sexually pleased by another woman? In fact, Sam is actually the jealous one. For instance, when we have threesomes with other guys, he doesn't like it when the other guy "kisses me too much."
I just want him to be honest with me and let me have a conversation with him about this without him getting angry. If he is in fact a Poly, then we need to reevaluate our relationship. Based on your knowledge and experiences, do you think he is? And how should I approach talking to him about it?