Spoiler! He tries to kill himself. It wasnt an accident. Shen Qingqiu
As i remember, it was an accident. The doctor advised that he should not be driving but he still did. So, when he was supposed to turn the car, he wasn't able to since his arms weren't that fully healed yet.
wait i thought he lost his memories like right after the accident but he still remembers him, so when does he lose them??