Should me and my girlfriend enter an open relationship?

I've been with my girlfriend for a little over a year now, and things have been mostly great. She goes to college roughly 4 hours away, but I visit her when I can/she sees me over breaks, and its going as well as a long distance relationship can. However, Ive been accepted into a much better college than I'm currently in as a transfer, 4 hours away in the opposite direction. She wants the best for me and wants me to go, but she still wants us to stay together. I don't think I can handle a monogamous relationship for at least the next 3 years, especially when I've never really been out of the area that much. I really do love her though and don't want to lose her. Thats why I want an open relationship, so we'll still be together but the distance won't be as bad. She thinks its tacky and a bad idea. What should we do?