I don't think that you need to feel guilty. It sounds like he is just changing. He is going through his own depression. He will have to ride it out.
Have either of you considered counseling? It sounds like you both could use somebody impartial to the situation to talk to. That is if he will.
I know that you feel sad because he isn't the way that he use to be, but eventually you will get to know him, as he is now and can still be friends. I just can't promise that it will be the same as it was.
I wouldn't blame your hard time to be what changed his attitude. It could just all be coincidental. He may have gotten depressed anyway and still would be acting this way.
I use to notice in my first marraige, that I would get depressed and when I got over it my husband would act depressed. It just seems to go that way. But I don't think that one causes the other, so try not to think in those terms.
I hope that this helped some,
Moderator-Depression and fibromyalgia
fibromyalgia, Chronic fatigue, depression,allergies