Over in the UK, the Conservative Party's families spokesperson David Willetts is concerned that marriage is becoming the preserve of the middle class, and that lots of people are simply no longer bothering to seek religious or state recognition of their relationships. As a "solution" he's proposing state promotion of marriage through discriminatory tax treatment, relationship lectures during civil marriage ceremonies, and a whole host of other intrusions into people's private affairs.
He should butt out. The state has no business in our bedrooms, and neither does it have any business in the form of our relationships. Provided everyone involved is a consenting adult, whether we are single, de facto, married, poly or swinging is simply none of their concern, any more than the gender of the participants is. They should have no role beyond providing a non-discriminatory legal framework for the attendant legal issues (next-of-kin / inheritance / property on separation). Trying to force us to conform to some preferred type of relationship with incentives and finger-wagging lectures is the worst sort of nanny-statism, and a gross abuse of state power.