Hey girls! A little help? What should I do?

You say that it wouldn't be "fair" to her. Why not? Doesn't she deserve to have all of the facts before committing to a relationship such as marriage? I mean if you tell her and she still decides that she wants the other guy, then what have you really lost? But, if you tell her how you feel and she decides that she returns your feelings, look at what you might gain?!