What are these feelings i have for her?

Several months a go I developed an intense crush on one of the girls I work with. I didn't initially find her that attractive when she first started, i mean she's pretty but i'm very picky when it comes to girls lol. But over the months I started to enjoy her company ever more and we mess around and tease each other in work. This all developed into an almighty crush wihich was debilitating and turned me into an emotional wreck. But the strange thing about it was that I hardly ever thought about this girl as you might expect someone with a crush to do. It was more of the way she made me feel when I was around her and wanting just to be with her that I was attrated to. But luckily she had to go away for a few weeks. In that time I was able to move on from the crush and get my emotions sorted out. So when she did eventually come back to work I didn't have the same intense feelings for her. But lately I'm starting to like her in that way again. I don't 100% feel attracted to her but there is some underlying feeling that I have for her. Maybe I will always have it because I had such strong feelings for in the past. I don't know whether its a feeling for the banter and friendship we have or whether its something more. I am very confused about how i feel towards her.

Maybe you just like the flirtation and attention.

Sounds intense. How important is your job to you? You could ask her out if you're willing to face the possibility of leaving your job if things go badly.

There is a problem in the fact that she has a boyfriend. Why is it the things we know we can never have that we want the most?.

If you like her all that much, steal her away from her man.
If not, then just stay away from her.
Not that complicated since it's only a crush.