This guy says he's really attracted to me, but he has a girlfriend.

Okay, so this guy is really attracted to me and vice versa. BUT he has a girlfriend, and so I won't even try to pursue anything with him other than friendship. But he still intensely flirts with me, saying he loves my body and my personality. That he thinks I'm sexy, and misses me, and thinks about me a lot even though we've only known each other for about a week. My question is, is he actually interested in me as a person or as a one night stand? I've already made it clear to him that I am not that kind of girl. Is it normal for guys to flirt with girls and say things like "I bet we'd have great sex?"