Why is dating this girl so hard?

I dated this girl I worked with briefly for about 3 weeks last October. We had almost nothing in common, but I was really attracted to her and we got along very well. We always had a good time together and we seemed to complement each other well, despite our differences. The last few days of the relationship I felt like she sort of sabotaged it and found an excuse to end it over something really trivial. I come to find out later that the real reason why she ended it was because of our religious differences. I am an atheist, she is a Christian. I embraced who she was and didn't care, but to her it was apparently a big problem. Who knows if that was the entire reason why she ended it or just an excuse. I tend to think that all women are out to manipulate me in some way or another, from past experiences.

After she left, she would text me from time to time. Luckily, she had quit the job we were both working at, so it was easy to avoid her. I would give her one word responses. She said she still wanted to be friends, I said I didn't want that. I was actually really hurt when she left me, even though we weren't together for very long.

Well, about 8 months later, she returned to our shared workplace. I gave her the cold shoulder at work. I ignored her, I tried not to even make eye contact with her. I felt betrayed by her, and even a little embarrassed. I'm 31 and she's 23 and, I don't know, it just made me feel like an old fool for even pursuing her in the first place. I was a little immature about the situation, I admit.

2 months after coming back to work, she reaches out to me and wants to see me again, saying she misses me and has tried to date other guys but can't stop thinking about me. I at first tell her no, as I was casually dating someone else at the time (which was pretty much going nowhere), but I thought about it and figured I would give her a chance. After all, I really liked her and my dating experience with other girls really sucked compared to the short time I was with her. I really did miss her. She told me she just wanted it to be like it was before.

But, it's been about 3 weeks since we agreed to start seeing each other and I've seen her a grand total of 2 times outside of work. She acts very coy and shy, not letting me touch her too much, doesn't seem to enjoy kissing me, and is very difficult to talk to. She wants to take it slow, and I get that, but this is nothing like it was before. In fact, she's acting a lot like she was acting the few days before she dumped me the first time. Why would she want to be with me just so she can dump me again? If she does, I'm ok with it. I'm expecting her to do the exact same thing as she did before, even though that's not what I want. I'm just being realistic, but as a result, I don't exactly trust her, and I'm trying to play it cool, but I really like this girl. Does she like me or not? I don't know if I should be patient or just give up. I feel lonely with her. I want to get to know her again and I want it to be like it was. We used to talk, laugh, make love, go out, do stuff. Now she just wants to lie in bed with me and watch movies in near silence. Like I said, it's only been two times that we've seen each other this go around, but it's driving me crazy. Nothing's happening, nothing is developing, and our schedules make it tough but not impossible for us to see each other more than once a week on Friday, after a long night of work for both of us, with her spending the night and the both of us returning to work the next afternoon. I told her I'd like to see her more and under different circumstances, and she acts completely aloof to this. I don't know what she wants. We still get along ok and it's not like it's unpleasant, it's just boring, superficial, and a little awkward--at least for me. I'm ready to give up. What should I do?