Even though everything seemed to be ok, Nightwing knew otherwise. They thought that he didn't notice the hateful stares, the way they falter when they said his name, hell, he even knew they where ignoring his attempts to talk with all of them.
It's been a month since Wally, and everyone hated Dick. Even if they don't tell it straight to his face, he knows. He lost his best friend and has been going non stop get him back, I mean why wouldn't he. After all, Dick should have nwen the one to die, not Wally, cuz Wally had too much to live for, Dick didn't.
He'd been cast out from the batfamily, ignored by the team, and worst of all, he had been abandoned by everyone he cared for. He is in a state of depression, and it's only getting worse. He will go far to try to get back his friend, even commit suicide.
Ps: I got this idea from @Homicidallunatic