Thinking of moving to japan?

In Two years time, me and my girlfriend will have been together for 4 years which s a long time, i am think of doing a japanese course for a year and 2 months. the problem with this is the the course will require me to live in japan for a year this is the the course will require me to live in japan for a year. understand i will have to talk to her about it before i decide. we are in a serious relationship. i understand that she will be upset because of this. she already knows relationship. i understand that she will be upset because of this. she already knows that i will be studying japanese at my local college. in two years i will have completed a entry level course in japanese. i am thinking in of telling her at 2013 christmas, 7 months before the course starts. I can't take her with me either. i would still be in contact with her though msn and phone. i also know this kind of ong distance relationship will be hard to keep long distance relationship will be hard to keep will she break up with me if i go? the reason im dwelling it now is so that i can prepare for whatever answer she will give me and why i want to go there is because it is something that i believe i must do. i know she wouldn't cheat on me and she knows that i wouldn't on her. i don't really like keeping things from her, but this i have to, for a while must do. i know she wouldn't cheat on me and she knows that must do. i know she wouldn't cheat on me and she knows that wouldn't on her. i don't really like keeping things from her, but this i have to, for a while