She has a boyfriend, so why is she acting like this towards me.?

I met this girl 2 months ago, started talking to her, and went out on a date with her. During the date she decided to drop a bomb on me and tell me she had a boyfriend (who lives like 700 or 800 miles away from her), even though I had been flirting with her and made my intentions clear. After the date I asked her in person why she agreed to go out with me if she had a boyfriend, which she replied with, "I don't know really... I thought maybe we could be friends". I didn't really want to hear that as an answer, so I left and told her I'd think about it. The next day I told her I was really disappointed that she didn't tell me sooner, and that with how I felt, I wanted to be more than friends. She accepted this, and that was the last I heard from her for a month or so. Now, a few weeks ago she text me out of the blue, and since then she has literally text me every single day. We talk about stuff we have in common (which we have nearly everything in common), but she still mentions her boyfriend once in a while (so I know she's still with him), but not a whole lot like one would expect. When we talk, I don't act like I'm still into her, and I really just treat her as a friend, because I don't want to keep her hanging around, feeding off the attention I give her, but for some reason she always texts me, EVERY SINGLE DAY...

Now comes the even more confusing part. She wants to come over and make me dinner tomorrow night. I don't get why she acting like this...