I don't want to be with my girlfriend anymore?

I have been with my girlfriend for over a year and we have been through lots together but I feel that I don't love her anymore. The spark isn't there as much as I want it to carry on and she lost all her friends to stupid reasons so I'm the only person she has left. Also, we live in Preston and we have both just finished our GCSE's and I decided I'm going to go to a college in Manchester and she is thinking about going to the same one so she has me to look after her but I don't want her to follow me to college and being so far away from her family once I break it off with her. I just don't know what to do I care so much about her feeling and I do like her a lot but I just don't want a relationship at the moment. Any advice?