JJ, did you feel that spark in the beginning and then lose it? Or was it never there to begin with and you tried to talk yourself into being in love with her because she was such a good person?
I've been in the latter situation and sadly, you can never really make that kind of thing work out without feeling like you're settling with something that's not enough.
You're so young, why settle down now anyway? Given the fact that you don't feel like you're in love with her, this seems like a recipe for unhappiness.
Don't you think your girlfriend deserves to be with someone who loves her just as much as she loves him? I say, let her go.
“Inside every cynical person, there is a disappointed idealist”--George Carlin