I wouldn't want a friend or a partner to be at any therapy-related things with me... it would make it harder to share and be honest.

That said, if he's saying to you that he's wondering if he has something... maybe he does. Some people are just really good at hiding their symptoms. Not everyone actually has their work or life severely impacted, like requiring time off. I've never needed time off, never had money issues, never been fired/on probation/etc... most of the time my friends won't notice how things are affecting me... etc. But yet I still have bipolar.

Stigma and idiotic sayings well, can happen even in people who are experiencing things. Just like how you will see females who are totally not feminist in any way - it's like they're against all the things that have been done to help equalize the genders. It comes from ignorance, but it doesn't negate a need for help. Why not just encourage him to go talk to someone for his own individual therapy?

Sorry that he's totally not supportive of you, I just wanted to give another perspective. The least supportive person in my life that I disclosed things to when I was going through seeing doctors for the first time... she takes anti-depressants to help with anxiety and depression. Yet she told me to get over the anxiety of seeing a doctor. I was floored with her TOTAL lack of any support or understanding and it pretty much ruined the friendship.