How Did Gabe Find Out?
When Gabe comes home for the weekend for college, Zack sneaks out of the house after spending the night with Shawn. Later, that night, Zack breaks up with Shaun. The next morning Gabe goes to Zack's work and tells Gabe he knows about Shawn and Gabe. How did he find out? This was never really explained.
I guess there might have been clues. Like maybe Zack's car was in the driveway when Gabe came home. And later he sees Zack wearing Shawn's shirt. But did Shawn tell him after Zack broke up with him? Or did he just figure it out on his own?
Same with Tori. How did she know? Jean, maybe?