Well there's one thing I can tell you, even if it doesn't answer your question specifically.

It's - in my humble opinion - totally okay, especially given you are not trapped in a delusion but quite aware of it. You say you are not an escapist, but I think this is a way of escapism. Not that it's bad, really - people need that, in a form or another. You probably have a great imagination and it's good if you're mature about it.

No, what the problem really is is that someday, you might meet someone who hits too close to what you're imaginating. And there's quite a chance that nothing will happen between you and her, because, well, that's how life is.

I'm afraid that if your "dream girl" constitutes your whole way of canalizing your romantic feelings, that day will literally crush you - because it will break your heart in the 'real' world, but also because it will render your illusion quite pale and dim.

I'm not saying you shouldn't do that; just don't make it an absolute, a finality.