One thing I haven't seen mentioned is whether you have been intimate with this chap, (sorry, don't mean to be overly prying)...if you have, this could be a real problem for the future of the relationship. You mentioned that he has a pending divorce, but in the eyes of a JW he is still married and would be commiting adultery if he was intimate with another person. This could be working on his conscience and creating his sudden change of personality. If he has been a JW for any length of time, this control can be very strong.
I would love to offer more encouragement, but I am afraid that most JW's, unless they are already mentally "out", will not make good relationship material unless you convert. Good luck in your journey through this chapter of your life...