I think you’ve boiled this down to a simplistic question when it’s not a simple situation. Ideally people work out that they have differing sex drives before they commit to a LTR and/or only pair up with someone with a similar appetite. However, world isn’t ideal, sex drives can change over time etc etc.
while marriage is based on compromise yadda yadda, simply saying this is a straight down the middle compromise situation is problematic as you are essentially telling the low sex drive person to have sex when they don’t want it… and since we’re all trying to do a little better with understanding both consent and coercive relationships nowadays (“you have to, you promised!” not winning chat up line of the year) it requires more nuance than that.
So the ‘compromise’ element in this situation is not so much A wants it twice a week (or 8 times a month), B wants it once a month, therefore (8+1)/2 = 4.5 shags a month must be had
The complex/nuanced concept of compromise is having some good discussions about how to avoid conflict in this area and looking at individual ‘coping’ strategies. For example - are there situations where B is more likely to be amenable to intimacy? Is A free to use porn/masterbation/toys on their own? Is there an underlying reason why either partners sex drive is ‘outside the norm’ and does that need addressing?
Is one of the stressors the actual act of A trying to initiate sex & feeling constantly rejected and/or B feeling pestered and crabby from having to reject - in which case, is there a better way of communicating desire/acceptance without having to go through the whole rigmarole of trying it on.
Slight side note but top tip I learned from a previous relationship is having clear language for non sexual contact (!) One of my favourite things is having a PG rated cuddle but ex always assumed physical closeness was a request/invitation for sex. After a while of having to stop him always trying to move things on (frustrating us both) we had a clarifying conversation (he hadn’t always wanted sex in those situations but was thinking I was asking for sex) and decided some clear wording for ‘just cuddles’ and ‘sexy cuddles’**
**not telling you our real phrases as they’re even more cringe!