My husband isn’t a lazy person but essentially does what he wants to do and not much else.
You say he isn't a lazy person.
Would you not agree that he is a selfish person?
He would do the things you do if you didn't do them, but he'd prefer to watch you struggle to do them and act as a separate entity to the family unit rather than as part of a team.
He may not be lazy, but that makes it worse, because he is capable and can get shit done if needed. He's just so selfish he would rather not make the effort.
Fundamentally he is my best friend and we are happy. But I guess essentially at my cost on the responsibility side.
Sunk cost fallacy.
If you could change five things about your relationship to make you happy, would he do them with no grumbles and keep doing them without being nagged, just to make you happy?
If you said look I've always done xyz but it's taking its toll on me now so Id really love for you to take it off my plate from now on... would he say god sorry I've never offered to help I didn't realise what a pain it is, talk me through it now and leave it with me from now on.
Because he fucking should and that's what a best friend should do but if you're honest with yourself do you think he would take it on board, be accountable for it and not see if he could get away with leaving it for you to still do?
You sound scared to rock the boat but if you're happy and best friends then you saying you're stressed and in need of a redistribution of efforts shouldn't rock the boat. It's what people do when they love each other.