Hi, if you think that there's the possibility that whatever he's going through might be
causing the distance maybe try talking to him about it (assuming he's worth it).
If it's really personal though there's a chance that he may not want to talk about it and need/want to work on/with it himself, so if you just let him know that you're there for him (and send him the odd text not expecting too much) that might help him a bit (even if he doesn't talk to you about it) or keep the doors open.
But IF it turns out that he's not being honest, you start getting REAL suspicions.......back to my original.......there's going to be someone better for you out there!!
Hope it works out whatever happens though.
Alison