This is the only advice I can give, and I mean it with all the best intent. It sounds to me like maybe you sort of put these girls on too high of a pedestal because you haven't experienced a relationship yet, and obviously really want to (don't blame you). The problem is, you're giving them too...
My problem is not that I believe my own existence has no meaning, it's that I believe no person's existence has meaning. That's why it's always so hard for me to break out of a depressive spell once I'm in it.