Sorry you're feeling so exhausted.
I wonder if your being a hinge between the men, or your being a woman, might have an effect so that you may easily become the one who gets the responsibility of things getting done, like the garden? I also wonder, since it seemed that it used to be that Mono was very helpful in the beginning of the co-habitation, if he felt he needed to "earn" the right to live there with you all, and now that he maybe feels more like he has the right, he feels he doesn't need to participate as much? Additionally, could the feelings of tiredness be a sign that you need better boundaries, in order to not give more energy than you are able to? Maybe you won't be able to give as much when you're going through stuff yourself.
Just some thoughts I had, I don't know if true in any way so take it or leave it. Take care.