emotional stress

Don't want to make this too long of a boring conversation for everyone. My partner and I have been together 5 years, for the last year and half my partner hasn't been working and has got his self into a depression. It's not something I understand and I'm really really trying to. I'm a very get up and go person and strong ( I thought ) he was going through a very hard time the past couple of weeks and I'm finding it increasingly hard to comfort him. I don't know why I really want to especially when I see he is hurting but I can't seem to break through my own barrier and do it. When we got together it was a bit shaky and certain things happen but I've also been in terrible relationship before and find it hard to let my guard down completely and it's so silly after all this time I know that man would walk on glass for me. But I just can't seem to let go and comfort him when he needs me. He has completely changed since we met. Since he hasn't been working it's like now he hasn't even got the drive too. It's driving me mad. I work a very complex job full time so I'm busy and when we have time he sleeps. He has his days mixed up with his night so awake all night and sleeps all day. I just don't know what to do. Is it me an I being harsh because of my own issues. I'm at my wits end. 😢