It doesn't increase financial stability, it's a sign that you've achieved it. Though, a married man may seem more hirable to a company, since they can presume he needs the income to support not only himself, but his family.
I don't see why marriage doesn't increase financial stability. Marriage is basically getting an incredibly efficient roommate. A spouse is a roommate that is fine with sharing a bedroom, a bathroom, can give you insurance, lower your taxes, etc.
