I don't want to be the complete grouch here, but this last part...
"Love is selfless."
And yes, it was so selfless the way that Erik kidnapped her, that he dragged her around by her hair and abducted her during Faust. It was also very selfless of him to threaten to blow up the opera house if Christine didn't agree to marry him. Perhaps he mistook obsession for real, true love. I can't really see Leroux!Erik being totally in love with Christine. I think he thought he loved her. I mean, she was kind, gentle, undoubtedly attractive, and had a marvelous voice. So it was natural for Erik to think he loved her. However, I must say that considering the life that he led, it would be hard for him not to be unselfish. And in the end he finally releases them, giving up everything he had worked for. This is why Erik is such a fascinating character. Should we love him or hate him?
Also, the beginning of your post. "She loved Erik because he was her teacher..." I think it was more of a general admiration. You can't not admire someone like Erik for all his talents and accomplishments. Although, I do agree that before Erik revealed himself Christine might have been a bit infatuated with him.
I'm not trying to spark an argument. I just love debating about Erik. He is so twisted and a wonderful topic of discussion.