Is it normal to love someone but have strong feelings for another?

Alright, so im in a committed relationship. Things are going pretty well id say, we dont argue much, our sex life isnt lacking by any means, and generally we are (from what I can tell, womaem are a tough breed to read lol) happy. Im not a cheater, nor have I ever been. Its just not something I was ever okay with, and she has cheated on past boyfriends but has been changing a lot of things to better her self and ive been right there with her through it and I have no doubt that she isnt and hasnt cheated on me.

In comes my boss. Normally, I wouldnt even give something like that a second thought, but for some reason, we instantly hit it off. I was attracted to her immediately, but like I said, normally I would forget about it. But this time its like I cant. We talk and joke a lot at work, and she even asked for my number (which now I regret giving to her) and we text from time to time.

Shes admitted to me that she also has feelings for me and would love to be in a relationship with me, but Ive explained how I love my girlfriend very much and couldnt do that to her. She says she understands and respects that but still drops pretty big hints sometimes.

I dont want to leave my girlfriend, and have no plans to do so. But I really cant shake these feelings. What should I do about it? Has anyone else been in a situation like this, or am I a dick for even acknowledging my feelings?