Lol so many people dissing that Yuuri suppose to make an equal standing with him. Dude he is "the son of prime minister and the next family leader head" and you want her (gyaru who is not very smart) to be someone with equal standing with a normal way? Like what? Study to be the top of the school and become student council president like generic romcom? In the first place keichi loves her because she is so reckless, brazen, and upfront about everything. It is impossible and out of character if she do a normal thing by equating herself with his standing.
Yes they are so crazy with each other and so over the top. But that was because it was their characters are like that from the very beginning, they really love each other and want to compromise for each other. And now you wanting them to be something they are not? Its funny if you think that way ffs.
If you think making her as butler is crazy, try to think about him arranging a school trip for both school to join each other so they can enjoy the trip "together". Do you think that is normal? No of course it is not normal for a high school student to do that. So this is just the way they are trying to make the relationship going because how awkward and crazy they are about each other.