that is a tough one. i think you have done just about all you can at this point. if the situation is intolerable for you - like the relationship becomes dangerous or unhealthy or emotionally,physically or verbally abusive - then you would have the leverage to say - get help or else...
otherwise - maybe an occasional hint/reminder that you are open to listen or discuss anything at any time. you could also get a book or two and leave them lying around - like Mike Lew's "Victims No Longer" - which he might pick up and benefit from - or ask you about - or pointedly ignore. if nothing else - it would help you understand what he is probably going through.
i know i couldn't be helped until i was ready. who knows why that happens at a particular time or combination of circustances or ...?
here is a link to a thread in the Friends and Family forum where i jsut posted a reply - it might be related. i'd suggest you also hang out there and ask around if you haven't done so already. most likely some of the members there could offer some insights from their experiences.http://www.malesurvivor.org/board/ubbthreads.php?ubb=showflat&Number=422584#Post422584
all the best -