Forsaking all others also means you prioritize your own children in such a way that your marriage remains the priority.
Marriage is a man and woman coming together and forsaking all others. If a partner in the marriage considers someone else equal to or greater than their spouse, that marriage is heading for the rocks, even if that someone else is an adult child. Adult children are supposed to be independent, gainfully employed, self sufficient men and women with partners and a life of their own. They are not supposed to be an appendage of daddy or mommy for that matter, and they certainly have no say in anyone’s marriage including and especially their parent’s marriage.
The only marriage they can have any say in is their own. The only marriage they can be equal in is their own.