@Jack244,
I think your alleged dream girl is going to find some other excuse next year.
As for the other one, don't go out with people if your heart isn't really in it. It's not fair to the other girl at all.
But I would advise you to look outside this so-called dream girl. She's putting everybody off, at least according to you. She might be serious about her studies (if that's the reason, then she'll only get more serious next year, and you will be put off again). She might be unsure about her sexuality. She might think all boys your age are jerks. She might be asexual. She might be super-religious. Who knows?
But I do think you need to think long and hard about what message it sends when this purported dream girl won't even hang out with you in public. Is she, perhaps, ashamed by you? Unwilling to show her friends and her peer group that you are friends?
Not very nice, eh?