Only he would know why he did what he did? If one treats it like a dream and wonders what "I" would do in his place, why I would do it; it is often easier to change directions and start new things when there is someone else with us? He may have been "afraid" about being promoted and moving and changing jobs, etc. but you were there and gave him support and the benefit of your counsel, etc. Once he moved, he did not "need" you anymore and, with his life in order for him, he did not want to take on having to help you and be with you and add you to his life? He used you, enjoyed you while you were there but that part of his life finished and he decided on a fresh start, was not thinking of you and how you would feel (he is in a new place with new tasks and excitement, etc.; think of how you feel when you start a new job or a new grade in school, you do not think about the place you left?).