Hacker News Reader

"We only considered couples who declared an anniversary date (as opposed to just changing their relationship status)"

Seems like a strange choice; most dating couples I know don't seem to set an anniversary date.

Many of my facebook friends (n~400, ~19 years old) are in a 'relationship' with their friends as a joke. Enough to skew any results.

I'm sure FB can distinguish between real and joke relationships with high accuracy.