A steadier ground guide to being the only one in the marriage who's caught up. What denial is usually protecting, how to move on practical matters without requiring agreement first, and when his refusal has started to put safety on the line.
Notice your own loneliness in the marriage before you decide to push the point again tonight. Wanting a partner in this is not the same as needing him to agree with you right now, and that distinction is worth a breath before the next conversation.
Before anything else: is this new since the diagnosis, or has he always managed hard truths this way? Some people have spent a lifetime avoiding difficult realities, and this is one more instance of an old pattern rather than something the diagnosis created. That doesn't make it easier, but it changes what you're actually up against.
Denial is rarely about the facts themselves. It's about what accepting the facts would cost. Accepting the diagnosis can mean accepting that he's no longer an equal partner in the marriage he built, that the future he expected isn't the one he's going to get, or that he's about to lose someone before she's actually gone. Refusing the word can be a way of not starting that grief early. It's also worth checking something uncomfortable: if he is also aging, is any part of his resistance actually his own cognitive change making the facts genuinely harder for him to hold onto, rather than pure denial? That's not the same problem, and it deserves its own look rather than being folded into hers.
Separate what needs his agreement from what only needs his participation, since far more falls into the second category than it feels like right now.
Note exactly which facts he resists: the diagnosis label, the need for help, particular symptoms, or all of it. Partial acceptance is common and worth mapping precisely, since what he can tolerate hearing about medication may be different from what he can tolerate hearing about driving.
You're allowed to grieve losing an equal partner in this before he's caught up to where you are, without that grief meaning you've given up on him getting there eventually.
This is what the tracking is for. Exactly which safety decisions are being blocked, and for how long, turns "he won't accept it" into something a lawyer or a therapist can actually act on.
Wanting him to be your partner in this is not asking too much. Whether or not he can be, right now, is not a measure of how much he loves you.