That's great! Ty! I'd like to start with TADC: Our Wonderful Lifetime since we seem to be on a role with that one.
So I thought that in chapter 7, both Jax & (DN) could team up to distract Caine and try to steal the key to his office. With (DN) being the first one to ask Caine if they could hang out to make up for that *date* while Jax tries to steal the key whenever Caine freezes. And maybe afterward, once everyone is gathered up, (DN) decides it only be fair if she writes a fairwell note to Caine to let him know after everything she loves him but as nothing more then a friend.
(I'm sure you already got the beach part covered)
And in chapter 8, is where Caine REALLY activate his yandere mode on (DN), as he is more persistent on hanging out with her and making her miss out on the majority the adventures. And because of that, that's when everyone starts to get more protective of (DN). You could even add a part where bubble accidentally mentions how (DN) kissed Jax in the lighting round adventure. Which would REALLY set him off.
What I think bubbles line should be: "You really were the lesser of the two, you ruined this. And worst of all, you let (DN) down."
And finally during the second crashout scene where Caine pits everyone into their own nightmare sequences, instead of giving (DN) one (since her worst fear is dying alone, which I'm not sure he would make), he trapped her in a ward and is forced to watch others suffer in their nightmare sequences. (It's like instead of suffering and dying alone herself, she's forced to watch others she deeply cares about suffer and die alone) And when Caine pins everyone down including (DN) she snaps and yells by the top of her voice: STOOOOOPPP!! And at the last second before Caine gets deleted, he sees (DN) on the ground shaking and sobbing for the nightmares to stop, making him realize that he really hurt the one human he loved and trusted the most.
And here's Caine's last words: Uh, wait. (DN) I...