Thanks folks. I did take your suggestion, vodkafan, and talked to him on our last date about how he felt about PDAs and what he had grown up with. He said that he was basically a conformist and wasn't comfortable with PDAs unless other people were doing them too. So I guess this means if we are at a party and other people are making out, he might too, otherwise no. I'm actually not sure if I can be comfortable with his attitude. He's to the point where if we're alone in a room kissing or cuddling and someone walks in (his wife, his roomie, or a friend), he'll immediately stop what he's doing. I can see how he wouldn't be comfortable cuddling me in front of his wife (the wife isn't comfortable with that either), but I don't see why he can't even give me a kiss with other people around whom he isn't married to.
This issue might be moot anyway. His wife just told him this weekend that she wants to move out. Poly was a way for him to still have a sexual and romantic life and and still remain married to his high school sweetheart, who has figured out that she's gay and no longer has any sexual or romantic interest in him. I don't think he has ever been comfortable with the concept though, and once she leaves him, I don't think he'll stay poly. He's already practically said as much, he said he would keep his options open if she left him, and of course, there are way more monogamous single women out there than poly ones.
I'm sad about the whole thing. I really like this guy. I definitely see him as a long-term secondary relationship I'd like to have. I'm very attracted to him and he lives 15 minutes from my house. I could fall in love with him easily, and I rarely say that about anyone. But I don't see this lasting.