HI Amy,
Although not spoken of often, another basis that the Watchtower leaders have allowed for a divorce is called "Spiritual Endangerment" ... but it is primarily intended when a married loyal JW has a partner who has turned away from the religion, becoming what they call "apostate." Were he to become "apostate" they would encourage his wife against him, leading her to divorce him ... BUT ... the problem you have is that he is trying to stay loyal to the religion and holding on to his less than happy marige. If anything, were his wife to be deemed an "apostate" he could divorce her ... however ...
That still does not technically free him to remarry. Yet, once this happens, many JWs have been very creative in obtaining a "scriptual divorce" by simply pressuring their partner to sign a statement that they are free to remarry ... kind of a loophole in the religion's rules ... no proof, no evidence, simply sign a piece of paper ... another loophole would be to hire a handyman to visit the house during the day when the wife is home alone, and have someone take a picture of him being there, and then by circumstantial evdience, the JW Elders will accept this as good enough to get a Scriptural divorce ... albeit a very dirty trick.
NOW FOR THE TOUGH PART: Run from this man like hell, never turn back, never feel sorry. Find a NON-JW and fall in love and marry him ... but don't marry a JW, especially one that sits on the fence, willing to have and affair, but whose loyalty is still stronger for this silly religion ... your life will be hell, and what you thought was love will get ugly and prove to be nothing but pure misery ... he either wants to marry you or not ... and he has already proven he does NOT. So please, run like hell, and let him go ... grieve the memory as you need, but ask God to get you through this and run for the hills ... run fast ... and don't look back. Ever.
Jim W.