Boyfriend is scared of commitment?

My boyfriend & I have been together for 3 years, we've just moved away from my home town on plans that we would start trying for a family an in process of signing documents to build a house.. now hes planning on going away for work for upto 1-2 years and saying he is sacred to commit but doesn't want to lose me?? Im confused.. he brought me all the way here to do this...