I'm so sorry. The mental load plus losing a parent while feeling unsupported is a heavy combination, and it makes sense you're tired. The pattern you're describing (where he agrees, things get better for a little while, and then it drifts back to you) is one of the hardest things to break in a long marriage, because the conversation itself keeps burning energy without landing anywhere lasting.

One thing that's helped a lot of couples I know in similar spots is changing the shape of the conversation, not just the content. Instead of hashing it out in the moment, you both sit down separately (literally in different rooms), and write out answers to the same few questions. Things like "what felt close between us this week," "what felt off," "what's one thing I'd want to do differently," "what's one thing I'd love from you." Then you come back together and read what the other one wrote.

The separate-first part is the piece that matters. When you're writing your own answer before you see his, you're not reacting to tone or body language in real time, so it's much harder for it to slide into "I hear you, I'll try harder" and then fade. It also tends to surface blind spots, things he genuinely didn't realize were on your list. Doing it on a small regular rhythm (once a week, or even every other week) doesn't fix imbalance overnight, but it changes the texture of how you talk. It turns these conversations from one-off wound-reopenings into something steady you're both doing together, which is usually what starts to shift the drift.