Once I moved on from the hoarder ex with 3 un-treated mental health problems, whose clothes literally covered the entire bedroom, floor and bed and all surfaces, well damn: I was a lot less depressed! Imagine a 1500 sqft apartment where 90% of the possessions are not yours, where if you see a piece of her garbage and toss it out, she'll get mad at you, even if it's a rotting, blackened orange peel. This sort of toxic relationship has to end, do not cling, do not "care for them" if they refuse professional help. This will sap your energy, it will sap your life, and you'll become depressed, unable to muster the energy to "fix" them or to leave the relationship. It was only when she went away for 3 months one summer, and I was marvelously not depressed and I didn't miss her one jot, I knew it had to end when she returned.
On top of that, I was in high-stress teaching jobs, $11/hr with no benefits in inner-city schools: this was important and impactful work, but brutal on the self. We actually got called racists by a very rowdy student, who wasn't allowed to jump on the desk and scream "I LOVE TACOS!" I'm not kidding, he called us racist for not allowing that. Never-mind the constant fights, religious students telling me science is fake, or having 35 kids in a tiny classroom. Teaching is a very important and undervalued field.
Once I actually got a $30/hr job with benefits and gained my freedom from toxic relations, suddenly I was the happiest I'd ever been. Add onto that, being in a relationship with a good match, with someone who had no undiagnosed/untreated mental health problems.