[nostrademons]

Strictly mathematically, it's not hard for a population split of 55-45 to result in a singles split of 70-30. Say that 35% of males and 35% of females are in a (heterosexual, monogamous) relationship. By definition, the numbers will be equally balanced, so of the remaining 30% of the population, 20% (of the total) are male and 10% are female, for a 66-33 split.

70% in couples seems high to me, so there's probably another effect at work. It's the same effect that makes it really hard to find a job in a recession: normally you might have 5% of the population out of work and 5% positions waiting to be filled, but if you suddenly have 10% out of work and 1% of positions open (companies that lay off people generally aren't hiring), instead of 1 person for each open job you have 10 people looking for each open job, even though 90% of the population weren't affected at all.