Perhaps a simple perk like grateful with maybe something that adds loyalty/obedience to anyone related to your wife as long as she's "head" girl since well, she would be the madam/matiarch of the household.
As a side note, poly should be a thing where you can have multiple wives. It be interesting to see wife "politics'" amongst the wives where they may even try to kill one another or the other's children, with them being successful depending on their stats.