Disclaimer - I'm pretty new to poly myself, so feel free to take my advice with a bit of salt.
For me, some of the red flags in your description of your situation are that he says that being with just you bores him, and that you say he looks at you with disgust. I'm going to use a food analogy - I love food, almost any kind of good food, and for me it is similar to my feelings on being poly. Let's say that for some reason I can't eat lasagna, but I can still eat cheesecake - both are foods that I love. Sure, I'll be a bit sad that I can't have lasagna, and if I could have lasagna it's possible it might even enhance my love of cheesecake. But that doesn't mean I'm going to not want to have cheesecake or that I'll look at it in disgust - cheesecake is good because it's cheesecake, I won't stop enjoying it just because I can't have other foods. They're different foods, with different flavors and textures, each of which can give me enjoyment in different ways.
Similarly, while I can understand your partner wanting to be with other people as well - I identify as poly myself - I have a hard time understanding how your partner is treating you. Certainly it can be difficult if you're having conflict over him wanting to be poly; when my partner and I first started discussing poly, it was over a woman we both knew that he liked, and there was plenty of discomfort and tension while we talked about how we both felt and worked toward reaching something that worked for us. But we still treated each other with love and respect, not disgust, even if we got pissed at each other sometimes.
Other's opinions? I ended up being open to poly, so it may be somewhat different in a mono / poly situation.
Keira Raven, married to husband Mal, interested in a woman for a triad or vee
(Previously known as Dakota Raven, husband previously known as Adam)