What is wrong with her?
A good young lady is not good enough, so she goes to be a little maid.
What's wrong with him?
There were many beauties around him who were throwing themselves into his arms, but they all paid attention to a little maid.
But this pretty maid has a weird nature, so she can't help herself...
In order to stop letting her "bring trouble to the world", he would reluctantly accept her.