I'm losing feelings for my girlfriend?

Okay here's the story, i been with my girlfriend for about 1 year and 7 months. I love her very much, but currently losing feelings for her. Were committed and all, I'm 18 and she's turning 17 this November. I'm starting college on august 29. I have a passion for film, were in summer right now and I'm planning on making movies. The thing is, i just really want to focus on my career which is film. I'm very mature, I'm not leaving her for another girl. This is very confusing, i would still love to be friends with her. I'm just afraid her feelings will be deeply hurt. Give me some advice please, Thank You.