Why does he keep doing this?

So I met this kid (I'll call him Mark) in my confirmation class. We started to talk a lot (mostly texting) and then whenever our confirmation class would hang out we'd talk and flirt and for my birthday he made me a cake (and people don't do that if they don't like you). So I started to like him, but I was afraid he wouldn't like me back (because I have terrible luck with guys). Eventually though I told his friend and his friend flipped out and told me that Mark liked me too. For the next four months we texted basically non stop, he said super nice things and just seemed like a fantastic guy. All of my confirmation friends told me that he wanted to ask me out but he was just too shy, which was totally true. He's really shy about that sort of thing, and so am I so I figured it'd take a while for anything to happen. Then one day, I saw him at church and he came up to me and hugged me and said that we were going to do something after church. I was so happy! But....the thing after church fell through, none of us could go. He texted me later and was like "I'm sorry the plan fell through, I feel bad. And I'm sorry I didn't tell you I was seeing someone else. I didn't tell you because...I don't know. I hope this doesn't hurt us being friends because I really love talking to you! Sorry about the plans again" I was crushed. He had been flirting with me and leading me on, when he ended up dating another girl. Now he still texts me pretty much everyday and sometimes still says nice things, but I don't get it because he has a girlfriend which means he doesn't like me. And I don't even text my best friend as much as Mark and I text. And sometimes I just don't respond because I feel weird texting him all the time when he has a girlfriend, But then he texts me again and again and so I have to respond because I feel bad and I just don't get why he keeps doing this. I told him he hurt me, does he just not want me to think that he's a jerk? (which i totally do) or is he just trying to stay on good terms? or is he trying to keep his options open in case him and girlfriend breakup? I'm really confused.