Question about a Leo guy!

I'm a Taurus girl with a bit of a situation on my hands, and I thought I'd check and see if you astrology buffs had any advice for me.

I met a Leo guy at the beginning of March on a dating website. We talked often (IM, messages, phone) and were very flirty with each other. Right away he was quick to warn me that he had been going on dates with a few other girls, and was very serious/highly concerned with my feelings and how I viewed that. I said it was fine, and we planned on going on our first date. Well, as it turns out, things got serious with one of the other girls before we had a chance to formally meet. He sent me a message and apologized, I said I understood and he had been nothing but honest with me, and we agreed to stay friends.

Well, we didn't speak after that. That is, not until last week.

Out of the blue I get an email from him, basically saying that he likes me and thinks that I'm beautiful and finds everything I post on my Facebook ridiculously interesting. That he's sorry he hasn't been talking to me, and he's sorry that it took him several drinks to work up the courage to message me. But he hopes maybe one day we can still get together and meet up, and would like to talk to me again soon.

I, of course, am assuming that Mr. Leo is having some regrets. I sent him a very nice, short and sweet, message back saying I'm glad he got in touch with me and we should definitely be friends and that I'd still really like to get together sometime. He responds with an even longer message asking how I've been, do I have plans for the summer, have I go on any good/bad dates lately, etc. Then proceeds to talk about how awesome his life has been, NOT mentioning his girlfriend. So of course, in my response, I ask about how things are with them.

He writes back an even longer message, discussing my answers to all of the previous questions and asking me more; seeming extremely interested in my life. I would have to say our messages are possibly even more in depth now than when we were initially talking. Then, when it comes to girlfriend, he tells me that things are wonderful and he's extremely happy and they just really "get" each other. Etc etc.

SO.

My questions would be:

Is he interested in me, or does he honestly want a friendship?
If his relationship is so great, why is he suddnly sending such lengthy letters to another girl he was extremely interested in a month ago?

I suppose I'm just very confused. Help?

Why are you entertaining this guy? He has a girlfriend. He is not your friend who lived next door while you were growing up. He is a man you met on a dating website. Show him the door. There are good men out there who are single. Focus on that.