It turns out that Bledel and Ventimiglia didn’t need to fake that obvious chemistry between their characters — they were actually dating in real life at the time.
Alexis Bledel And Milo Ventimiglia
Bledel didn't have to fake chemistry with either of her character's high school boyfriends because, just like her on-screen counterpart, Rory Gilmore, Bledel dated both.