I think the message of Howl’s Moving Castle is that in order to maintain a successful relationship with some kind of fucked up wizard, you must find it in yourself to also be some kind of fucked up wizard.
See, I don’t think that’s the case. Certainly, Sophie’s magic is often more practical than Howl’s, but if you think that the practicality of one’s magic is a reasonable measure of how good a fucked up wizard is at being a fucked up wizard, you don’t understand fucked up wizards.
By some metrics, Sophie is a more fucked up wizard - Howl would never mess something up by accident! But here’s the thing, they complement each-other. Sophie is practically-oriented, but she’s not always competent to do what she intends, nor does she know what she’s doing. Howl always knows what he’s doing and why, and it’s usually useless bullshit for terrible reasons. Howl knows what he is intimately. He knows his strengths and his weaknesses and he knows that he’s got a spine like wet, single ply tissue paper. Sophie complements this by doing whatever it is she sets her mind to, but having exactly zero capacity for self-reflection (or if she does it’s through a funhouse mirror)
Your honor, they’re both a better fucked up wizard than the other, just how they’re supposed to be.