He has a girlfriend but...

I'm interested in a guy that already has a girlfriend... but I keep getting mixed signals from him. We've drank together in a group setting a couple of times, but when we're sitting next to each other, he's either leaning his leg next to mine or leaning his entire body on mine. One time, I had my arm hanging out while I was sitting in a chair, and he started to tab lightly on my hand with his. He either leans in and talks in my ear or leans in closer to me when he talks to me. I finally got his number and started to text him. Sometimes, he'll read it and reply right away but other times, he'll read it and not respond. This is why I get mixed feelings. He brings up his girlfriend sometimes when we're drinking. They've been dating for about 3 weeks but he'll tell me that there just aren't any sparks between their relationship. The first time he brought her up, I just told him to try to do his best to be with her and make her happy but once I started to like him, I just straight up told him to break up with her. He'll sometimes be like "Do you think I should just break up with her?" but sometimes he'll say "but I want to try and make it work." I really want to tell him that I really like him but also don't think it's the right thing to do. Please help me out.