The Jesse Quick and Nightwing dating incident is actually so funny and bittersweet.
So Wally finds out that Dick (his best friend) and Jesse (his pseudo sister/cousin) are dating and he's obviously not thrilled with that. So he does the what he does best and tries to annoy Dick into not dating Jesse (by following him around at superspeed and putting wedding decorations everywhere).
But then he finds out that Dick and actually rejected Jesse's advances and that he was really upset that she quit the team. Wally, reassured that they weren't dating and seeing how depressed Dick was about Jesse, immediately went "I CAN FIX THIS".
If Wally telling Dick that "change is good" and that we don't "survive, we thrive" sets off warning bells for anyone else, good, it should. Wally knew exactly how to get Jesse on the team. He had to quit.
(Dick and Wally had a bet going. It was an attempt to get both of them to stay on the Titans together. Ten dollars to the other if you leave)
Needless to say, Dick was not happy about this. Wally did what he did best and he smoothed things over with Jesse. He got her to agree to coming back to the Titans as long as he quit.
His 'own reasons' are that he'd do anything to make Nightwing happy, even give up his spot on the Titans. Also, he knew that Jesse needed to be on the team. She was not in a good place.
So Wally left the Titans without a word, Jesse was back (still with her crush on Nightwing) and Dick had somehow managed to trade one speedster for another without meaning to. Look at his grumpy little face. He's so mad about this.
SIKE
Wally came back to say goodbye.
And then him and Dick had a heart to heart about how Wally joined the Titans for Dick, to comfort him, but that Wally knows that Dick loves the Titans and that he'll be okay without him.
Masks off, watching the sunset together. Thats a beautiful bromance ladies and gentlemen.
