I admit I couple be wrong but I implied from the OP, "Last year they stopped antidepressants. They have been stable but last month has been
signed off byGP for anxiety and stress." I impliedthat it was a reasonable decision, which at the time she did not oppose either and neither did the GP oppose it (I'm also assuming that the GP know this - so likely would have somehow supervised it, or
intervened if they had concerns, as it seems they have a good relationship with the GP(s).
Also stopping medication isn't always bad - unless done abruptly but that's more about side effects and withdrawal. Done well, over time it can be positive and can be negative. It clearly was fine for almost a year. He could 1. Be sufficient without them and want a break 2. Think the dosage wasn't worth the side effects etc.
As @Tessisme mentioned "Just because the person can do some stuff sometimes, doesn’t mean they can participate in anything involving expectations and responsibility, particularly when stress is a factor." Depression is complex and also it can be hard when you got better to them relapse and come to terms with that again -it can be difficult as some people see that as they'll never get better and they're descended to fail.
Especially since the OP mentions how he hasn't had an episode since he's been with her -it's hard to have an episode around someone you love as you feel worthless and like they don't want you around and they don't like you.
So,it's hard to engage with the family. That being said, it's only fair if the OP let's DH know how she's feeling, and they have a conversation resetting boundaries and expectations and explaining how they both are feeling and trusting each other to work together. For DH that would also involve trying a new therapy (DBT seems like it would help), getting back on ADs (now ones or the same but higher dose) and also seeinga psychiatrist for a whole new assesment, to see if anything else is suggested. For OP, that's also learning more, really reading research on how to help someone with MDD and doing that, perhaps them both trying some occasional couples therapy, communicating with DH properly.