That's the thing about attachment; it creates an unrealistic image of someone. Like you said, what she wants you aren't capable of giving and it's not your fault. It's the unreasonable expectation that you should be something other than what you are.

I would suggest sitting down with her and explaining gently that you just aren't capable of being everything she deserves. You love her and want her to be happy and that she would be happier with someone who can fulfill her needs. It would be best if you guys stayed "hands-off" to avoid her developing that attachment any further.

Sorry Best of luck.