A friend of mine is about half way through a PhD and seems to be having a very tough time. I'm worried that he has started to suffer from depression. I had depression last year and I'm seeing a lot of warning signs - he's having trouble sleeping, he's very negative about things, he doesn't seem to enjoy things much. I know from my own experience that if he is becoming depressed he needs a lot of support and he needs to recognise what's happening. I've already said to him that I'm a bit worried about him and I've tried to reassure him about his PhD (he's convinced he's going to fail) but I know that's not enough.
I'm wondering if I should talk to his girlfriend? She's really lovely but I don't know her very well. I'm also wary because he's a very "manly" man and seems to think that he just needs to pull himself together, which is obviously not possible if he is genuinely ill. I'm afraid if I do talk to his gf he'll see it as interfering. On the other hand, I know how bad depression can get and I really don't want him to end up like that. There's only so much support I can give him directly as I have a young son and don't have much free time.
Any advice?