Most girls, and everyone in general, when they start college, are starting a new beginning. The have a whole world of opportunity ahead of them. It's not the time in a person's life to have any tie-downs like a boyfriend back home. So, basically, once she hits campus, she's gone.
Also, did you ever consider that you mis-read her? She may put you on the friend ladder and not the real ladder. See the
Ladder Theory for this.
There is one last hope. She may get desperate or bored while at school(not likely) or home on a break(very likely). Then she'll remember you and find your number. That's your only chance as I see it.
BTW, what's the age difference between you two? And like everyone else said, don't get all worried about it. "I've got 99 problems and a bit*h ain't one."
