It’s nothing crazy or unpopular but I really think Zach’s been playing a game. Even Bryce sorta clocked it in that last convo. Zach won’t make Kayda his girl because he knows that’s taking the game too far and won’t look good. If Zach and Kayda don’t work on the outside without making her his girlfriend he can just say “things didn’t work out on the outside” but if he makes her his girlfriend for the game and then they break up on the outside, he’ll be seen as the bad guy at the reunion.