It was a month after Bart Allen
discovered his secret, and the two of them fought, that Arthur finally
confessed to his best friend, Victor Stone. Arthur had leaked the location of the
Edge Gang's hideout to Lucas Luthor, brother of Lex Luthor, someone he had met
a long time ago while gambling in
Lex ordered his Legion to wipe out the Edge Gang, and then to plant explosives at their hideout after the job was done. The explosion caused a fire that destroyed several surrounding buildings, including a children's hospital.
Upon hearing this news from Arthur, Victor said nothing. He walked into Oliver Queen's office, said a few words, and then left the Agents of Justice gang forever.
Arthur stayed on with the Agents of Justice for two months. But eventually he began to wonder what was worse: the dozens of deaths he caused with his carelessness or the fact that Oliver didn't seem to care anymore. He headed to the nearest dock.
When he got there he found
Arthur didn't want to leave. He wanted to be strong like
Arthur said "another time". He smiled, waved goodbye, and dived out into the ocean.