"Guys have just been hookups," the classmate tells Us. "With girls, there have been actual relationships."
Glassman, 22, -- the daughter of the plastic surgeon who performed Kate's free tummy tuck -- went public with Jon, 32, by holding hands with him before boarding Ed Hardy designer Christian Audigier's yacht in St. Tropez last week.
Jon reunited with Kate at their $1.1 million Pennsylvania home earlier this afternoon.
On Tuesday, shortly after arriving in the United States, he told photographers that his girlfriend was staying in France and that he had to come home to "work." (He said he still has 34 more episodes of TLC's Jon and Kate Plus 8 to shoot.)
For more details on Hailey's wild past, how she and Jon first hooked up and what they did on their all-expenses paid getaway (their luxe room cost $2,515 nightly!), pick up the new issue of Us Weekly, on stands now.