Welcome to beyond blue.
You asked at the end of your post about whether your partner goes to a psychiatrist. I will give you the answer my psychiatrist gave me.... medication can help, but also do talk therapy is better, and leave the head stuff to the psychologist . ie to do both. I do find ADs helpful for myself.
Of course some psychiatrists may also do work similar to a psychologist but the sessions with my psychiatrist are only 30min vs 60min with my psychologist.
My father has been taking ADs since early 90s, and never spoke to anyone about his feelings. Only how is he seriously thinking about going to a psychologist.
I have been seeing a psychologist for > 1 year, but keep in mind that my situation is something I have lived with for about 30+ years, only now am I starting to make in roads. Some people might do it more quickly. Some more slowly. It takes time and patience. But with all of this, your partner has to want to do it.
It is also possible there was a mismatch between your partner and psychologist? And maybe a different psychologist would be better?
You are the definitely a very caring person and your partner is lucky to have you. There is always a danger it can affect you as well. There are also resources on the beyond blue web site for partners here...
which includes information on the last pages about looking after yourself.. There is a lot in your post that I have not responded to, but I hope that you will come back to tell more of your story.
Is your partner able to talk to you about how he feels?