And she can quit you.
Whenever either of your self-centered priorities surface, even if you are married, at least in the West. I'm not thinking of other places.
Marriage is silly without a fair amount of understanding about the world and interpersonal relationships. Pursuing this without these prerequisite means you are simply trying to satisfy some outside dictate to be deemed worthy. As such, it's a fake blessing, be it religion based or state based. Children are in flux, which is sort of related to why so many (not all) of our (theoretical) relationships with young girls prove not to be permanent.
Am I hotly against marriage in these cases? No. I just think it's silly and pointless, and possibly even not respectful to the idea of lifelong commitment.