Advice please !!!!

My boyfriend is moving to Kansas in a month for a job we don't want to break up but we both know long distance realtionship won't work. He asked me to move with him I told him I wouldn't do it unless we were married long story short he proposed to me a couple days ago I want to marry him but I feel like he doesn't mean it. What should I do? I'm 18 and he is 26.