If he is struggling with his beliefs then it will be a difficult time for him. If he was or is a JW when he was dating you a non JW then he would have been in conflict. His belief system does not allow him to date non JWs. He would have had to have kept your relationship a secret. This is not sustainable in the long term because after a while the non JW is seen to be the start of and cause of all the difficulties and in order to be welcomed back into the fold the relationship must end. Because you are seen as the cause of the problem and because you do not share his beliefs he will not confide in you or ask for your help.It is extremely common for the non JW to be shut out whilst the person seeks to resolve their problems.
If he is vascillating because he wanted a relationship outside the confines of his faith then he is not truly free of it. He may still believe and in that case all you can do is walk away for your own sake and peace of mind. If he no longer believes then that is a different matter. The organisation does not allow anyone a dignified exit. You either tow the line or get out. The guilt and pressure to conform will be enormous to such an extent that if he leaves he can still be drawn back by any sudden trauma in his life.
I would suggest that you set aside any ideas of a relationship. If you want to help him as a person all you can do is ask himn if he wants to talk about it. Don't issue any ultimatums. But the chances are he is already pulling away from you. Assure him you are there as a friend if he needs you.