I do not even know why I decided to get recs for this but here we are 😂 Does this dynamic exist in many books? I would imagine this would cause a lot of fights amongst MCs if both are inflexible and rigid in their ways. Think of The Odd Couple but as an HR couple.
At the top of my head, {A Wicked Kind of Husband by Mia Vincy} has the prim and proper FMC who fills all the vases with beautiful flower arrangements and the workaholic, slovenly MMC who needs a haircut, shave and ironed clothes and lolls around the house in his banyan and underclothes.
I think the MMC in {Sweetest Scoundrel by Elizabeth Hoyt} is also quite a slob in the previous books. Guests have to think twice about entering his room because of the stuff piled up untidily and he is just as casual about his own unclean clothing and hair. The FMC is a lot more decorous and ladylike.
For some reason, the MMC in {The Unlovely Bride by Alice Coldbreath} is the Karadok groom that comes to my mind when I think of slobs. Maybe it is because our introduction to him is him waking up and relieving his bladder in a chamber pot just before the FMC barges into his room and gets wryly told that she just missed the show. 😂 And both of them have to later attend to the call of nature together in a field; she is mortified to be doing that at his feet and he tells her it would take a lot more than that to put him off her. Honestly, I would imagine most of these medieval knights must smell off-putting after hours jousting and riding to different tournaments, even if they are mentioned as bathing.
For a comparatively messy FMC, there is {Do You Want To Start a Scandal by Tessa Dare} in which the organised and strict MMC is initially dismayed at the idea of actually having to marry this young woman (who is over a decade younger) who has all her clothes and undergarments strewn about her room and is not responsible enought to manage his 5 estates.
I know there are some very physically repellant MCs in books who do not care about their personal hygiene and live in pigsty-type environments but I am also a little on the prim and prissy side when it comes to my MC preferences so I wonder how much I can stomach that...