She is straight, had feelings for me but couldn't accept that??

I am a lesbian. There is this straight girl that I fell for. We got very close really fast. So I told her how I feel about her. She was not surprised at all and said she knew it but she is not a lesbian. I didn't push her and I did NOT say anything about it again (which I regret so much). I was not sure if she liked me as she always says that she is straight af. Until my friend told me that she admitted she had feelings for me too.

All I want to know is

Is it possible that you can love someone but refuse to be together with him/her because of your sexual orientation? If yes, were you really in love with that person?

I have never thought that sexual orientation could be bigger than your own feelings.