Blovest;
I am a sufferer and I've read your post a couple of times and not replied as yet. Perhaps because there is no easy answer.
Is he in treatment? That is imperative that he commit to treatment 100% or he will likely get worse.
Is it combat related stress? Even harder for you to relate to as a carer.
Is it childhood abuse........well, then he's been ill a long time.
In answer to the 'happy' question.........well, when one has suffered intense trauma and developed PTSD.......'happy' just doesn't really exist in our reality. The brain undergoes changes that cause us to be constantly on guard for danger........there's no talking us out of it rationally. It is a response that occurs from the reptilian part of our brain. Doesn't even run through our rational brain.
Now, I ask you, if you were constantly on alert and in fear of your life with high levels of adrenaline constantly running through your system.........where would 'happy' enter the picture?
I suggest you read the list of suggested reading material. Support him in a way that doesn't judge or condemn, develop a thick skin and understand this is a chemical thing.........try not to take it personally.
And last but not least........certainly take care to get your needs met. If not and it is stressing you and causing your life to become a living hell also........well, that's not good either.
It's a tough road for carers.........but with treatment and understanding........it can be done.
Best of luck