Let's examine the title of your post, shall we? I think it's summed up nicely there:
Exhibit A: "She still loves me"
Exhibit B: "She wants to see someone else"
Now, I'd say those two are mutually exclusive. She really has relagated you to insurance policy. She's a junior in college, and is going "OH MY GOD! I'm a JUNIOR in college! What the hell am I thinking going to get married! I don't wanna have to cancel Cosmo and start reading Redbook!"
The urge for her to sow her wild oats has taken hold, and unfortunately you're left holding the short end of the stick in this situation. But let me clue you in on something: she has just saved you years of greif and a very messy divorce by breaking up with you now instead of when you were married. I know she's your first girlfriend, and you always fall the hardest with your first love, but as people say- there's your first love and then there's your true love, and very rarely are they the same person.
Best of luck- I know it's hard now, but just smile and get on with it, and the perfect woman will come your way- one that won't leave when the going gets tough
