This is not practically true. Imagine if the same could be said for romantic relationships: "You can definitely be prepared for what cohabitation/marriage is l

This is not practically true. Imagine if the same could be said for romantic relationships: "You can definitely be prepared for what cohabitation/marriage is like before your first relationship. It may be a lot of work, but it is not beyond comprehension." Yes, the brain is capable of comprehending life in cohabitation, as proven by the current mental state of all who are currently in the situation. Getting to that mental state without experiencing cohabitation is practically impossible. Now swap out "romantic partner" with "small person completely dependent upon you for survival for the next 18+ years".