I feel for you OP, my other half (we don't live together) has severe narcolepsy, we barely see each other and as it currently is if he is awake for 8 hours out of 168 per week it's a good week.
The falling asleep in early evenings could be stemming from a sleep disorder or it could be CBA and avoidance of cleaning up. Does he have excessive sleepiness during the day? Is he relying on caffeine etc to get him thru?
OH had a good job, about to take over the family business, making good money when he started sleeping more and more firstly in evenings, bedtime was earlier and earlier, sofa to bed, late up in mornings then mornings became afternoons.
It doesnt matter how much he wants to do/go/see whatever if he looks forward to it its a higher chance it won't happen.
He wasnt with it enough to eat, drink or go to the toilet. His bladder is ruined from urine lying in it for days, he literally has no lining left in it. His stomach has shrunk as has his weight dropped from 17st to under 8st now cos he hasn't time to eat. His bowel has stopped several times as his body was in sleep.
He collapses to the ground if he has a strong emotion of any sort, he nearly has had "death by drowning in cornflakes" a few times by losing all muscle tone and face first into cereal because he laughed at something or thought about something funny.
With losing muscle tone he has been in a coma-like state in hospital, where I overheard 2 Drs saying I was denial as I insisted he was in a deep sleep and we were there cos of muscle tone or lack thereof. They insisted he was in a coma.
"Lazarus" woke up, sat up in bed, pulled drips out, wrapped himself in a sheet and went belting down the corridor cos he needed a smoke. Shouting that everyone was staring at him, mainly cos they had been trying to elicit a response for over 12 hours and "Lazarus" was running going for a smoke with me hot on his heels to keep him right.
We are fighting to get the treatment he needs but it's expensive and getting it on NHS is the stumbling block cos £££
OP If your DH has a condition it will do both of you good for him to have it investigated and treated and get coping skills for living with it,
if however, he isn't prepared to go back and get tests and other opinions, (cos something to hide) then I would say he is having a case of lazyitiz and letting you do all the work and only finding time for the things he wants and as not prepared to try to make you happy pending no medical reasoning for this, you would be better off without him.