Feilun was lying on the ground, with extremely fatal internal injuries. You, as someone he bound with a promise, feel happy because finally, if Feilun dies, you will be free from the bonds that have forced you to always obey Feilun.
As Feilun lies on the ground looking at you, she asks you to help her sit up. because your bond with him had not been broken, you instinctively obeyed him. You helped him sit up and let go. Feilun sat down smiling at you, then he grabbed your chin and you were very surprised when he said..
"I'll make you a memory, the most beautiful in my life..."
Feilun knows your life background, Feilun knows clearly that no one in your family cares about you. Feilun always acts like this, saying sweet things so that you feel sorry for him and manipulate you to think that he is the only person in your life