By reading this thread I can only say my husband and I have a hybrid financial understanding.
We have separate checking accounts, but we also have joint checking and joint money market account.
Money market was used primarily for escrow shortage bill we knew would occur (and were putting money away in that account) since our house was newly built and we didn't have the taxes that first year. Now the money just sits there (earning a bit but not much interest) for when we get the now much smaller escrow shortage bill each year.
Joint checking is primarily used to a) transfer money between his account to my account and my account to his account b) bills as well as life insurance policies we have for each other. It also earned a bit but not much interest.
Separate checking accounts is where paychecks go into. We would split bills according to our income. My husband made roughly 60% more than I did. Sometimes he picked up the whole bills depending on the situation. Car payments (which only my husband had but he has since finished paying it off), student loan payments, credit card payments,car tags, etc all were separately paid by our own checking accounts. My checking account when we got married had been in existence for almost 7 years at that point (It's now been 11 1/2 years). I had the longer history with the bank (we have our accounts at the same bank).
Whenever we got bonuses they were no where near what the OP is getting but there is just no way in the universe my husband would spend that kind of money without discussing it with me first. And this would be the same if the roles were reversed. We have always had an understanding that lower amount purchases don't need to be really discussed. You want to buy that $120 on special windows tablet with your paycheck? Sure fine no worries and you don't need to ask my permission to do that. You want to buy a $500 tv--yeah that should be discussed first.
We are also different in that my bonuses minus the 40% tax cut went to my student loans; you could also defer a portion or all of it to 401k if you wanted to. His bonuses usually went to that as well or in his checking account for usage later like vacation, etc (which for the entirety of our 10 year relationship he has shouldered most but not completely all of the vacation expenses--on the other hand I'm always on the lookout for spending less $$ on vacations in general). If we got a bonus for like $25,000 we'd probably use that to pay down (or payoff several) student loans, nice payment for the mortgage, etc.
As far as what the OP wants to use the bonus for that really should be discussed first..not even really considering the cost but that to me it seems the right thing to do. Now discussing doesn't mean asking permission. It just means "hey honey I'm thinking of getting x,y,z with the bonus I'm getting what do ya think?" Surgery can be risky and can drastically change one's appearance (and at times that's exactly what you want). Now yes her body is her body but it would be the same if the husband wants to do something like that as well. Certain things, at least IMO, should be discussed.
If the OP never had 'shared' the bonuses then the discussion of how much the husband is getting wouldn't be there. If you shared the bonus one or two times over the course of your entire relationship then I wouldn't say there's an expectation. But the OP seems to share year after year after year. Changing this agreement should at least be given some consideration to what has been working thus far in this 20+ marriage the OP has had with their husband.