You have only so many choices here and one question I have is what does your boyfriend think? It's really critical to get his input on how he thinks this will work during the time you guys are apart.
1. You stay boyfriend and girlfriend in a long distance relationship and keep in touch as best you can with Skype, text messages, etc. You need to trust each other enough to do this. You also need to agree that you're mutually exclusive (meaning, not dating anyone else) during this time.
2. You break up temporarily during his absence and see where things stand between you two when he comes back. It could be that he will stay in New York once he gets there. You don't know what the future holds.
3. You do nothing and let things remain status quo.
I'm not a fan of just ignoring the situation. I want to know where things stand, so if this were me, I would have a conversation with him to see what he's thinking and for you to share what's on your mind. Good luck.