He needs a play mom for his play child
She needs a play husbabd to look like suspicious and more like a modern avg woman.
Arranged marriage by the elders of their corresponding families.
She gains protection.
He gains satisfaction for some mental issues
She needs physical protection and a way to travel safety while she tries to find her way back home.
What better candidate than a mercenary who knows his way around.
Shes a "weird" girl and was taught to physically defend herself.
Hes from a weird ass family and needs a wife whose able to protect herself from them.
You see where this is going right?
ML uses the normalcy of harems to build an entourage of skilled/smart women to help him overthrow the royal family right in front of their eyes.
He doesnt have to deal with his ex wife
She doesnt have to deal with her father
SPY x FAMILY