I think the study is about right because the average age in the interviews were 21 year olds.
Regardless, I think it is healthy to have other platonic relationships with friends of the opposite sex.
While this post was precipitated by the recently discovered love letters from President Warren Harding to his mistress, it really is about the proliferation of social media and how it impacts modern relationships.
Simply put, humans have always had back-up relationships – friends to whom they’re attracted, ex’s that still linger, unrequited crushes that have been buried for years.
It didn’t turn out that way: The average number of back burner relationships for the two cohorts was about the same.