"biggest questions are for those of you who have s/o's who don't suffer from mental illness and/or aren't aware of how it works and how to deal and cope...how have you as a couple made efforts to have one or both understand each other better and how to cope with mental illness before it drives you apart permanently"

I am BP and my husband is not. He understands on a basic level that there is something biochemically wrong, and I don't always think right.
I do not share my day to day struggles with him I come here to talk, or talk to my T about it. So I don't involve him on that level and it seems to help our relationship that he doesn't have to feel responsible for my mental health, I am.
If I am having a super bad time I will share that with him, so he knows I may be super sensitive, or may go off on a tangent about things, and to just let me be.
When I feel good I will do little extras for him-making a nice meal, or asking him about his day or what he is passionate about, showing an interest. That helps too.
It takes two to argue so if he says something that irritates me, I just walk away, take some breaths, and let it go. If it still bothers me the next day, I may bring it up, when I am feeling calmer,but usually not.
I hope things improve for you.