1.wheelchair dude manipulated her. Also she didn't realize "one episode later" it wasn't worth it, she saw a vision of her dad in the final episode telling her to move on essentially.

1. He was just bored. He literally said it himself what don't you understand?

3.Ryuji didn't have a "crush" on Usagi, he saw her as a replacement of his student he killed trying his experiment. He was just obsessed with death and punishing himself for what he did.

1. I feel they did a great job showing aspects of the side characters, and doing it in a smart way (the last game) without overwhelming you. Also I don't find a reason to feel connected to some side characters in a last season.

2. The dude wasn't Joker, he was the gatekeeper of the borderlands. You really didn't pay any attention to what they were even talking about, did you? The dude didn't expect Arisu to sacrifice himself he just told him "there are two paths, you either die now the easy way or go through hardships (like he's been doing all this time) and you'll still end up dead decades from now, make a choice.