After the whole sex tape dilemma in season 4, Haley freaks out and obsesses over all the girls Nathan slept with before getting it on with her, if I remember correctly, and she wants him to write a list including the names of all the girls he has ever slept with.
In season 2, however, which I recently rewatched, Haley found out about Nathan's stunt with Taylor and Nathan offered her to tell her about all the girl he ever slept with, hoping it would make her feel better. Haley, however, refused.
I love season 4, but this made little sense to me. You could blame it on the hormones, I guess. What do you think?