The marriage gap is always a low priority when news websites put up their exit polls. Everybody knows that`s not an important gap, not like the colossal gender gap, so nobody pays attention to it, so next time, the marriage gap isn`t give much play either, and so forth and so on forever and ever amen.
After checking a number of outlets, I finally found that the Washington Post has an elegant exit poll demographics page that does have the data.
Romney v. Obama
Married Men: 60 - 38
Married Women 53 - 46
Non-Married Men 40 - 56
Non-Married Women 30 - 68
From this, just guesstimating, until somebody puts up the exact numbers:
Marrieds (both sexes): 56 - 42
Singles (both sexes): 35 - 62
So the marriage gap is around 20 points, maybe higher.
In contrast, the famous gender gap was apparently about 9 points, or less than half of the marriage gap.