They met because of gay friends, and ended because he (Cheng Chen) turned into a vegetative state in order to save him (Su Zhuoyou). For him (Su Zhuoyou), he (Cheng Chen) may be the only one who puts his heart and soul into it.
Cheng Chen: 'I really like you, very, very much, will you accept me? '
Cheng Chen: 'I am willing to do anything for you'
Su Zhuoyou: "Because of that message, I am willing to wait for you until you wake up..."
Intention: Love someone as long as he is happy; even if you can no longer talk to him