It wasn't actually Xie Jie who was too horny and perverted.
Sure she felt turned on after seeing Bai Long's huge dick. But, just that wasn't enough to make her want to cheat on her husband so soon into marriage.
However, since the time she saw Bai Long's dick, and compared it with her husband's, whose wasn't even a third of it.
Xie Jie couldn't help but peek at the two having sex.
The first time she saw them, Xie Jie began dreaming of that huge dick inside her. And that was it.
She only fantasized about it, and didn't have any thought more than that.
But, after the second time she saw it, during which Bai Long had fucked Lanying for a much longer time, and even after she fainted he kept on fucking her, Xie Jie who was peeking at him for so long started to change.
It wasn't due to watching Bai Long have sex. Instead, it was due to the effect that his Constitution had on her.