You felt all alone and being an ignorant person to everyone then when Donghae came, he change you. Donghae didn't give up. He continue to persuade himself and his effort is not a waste. You found out that he is really nice, even if Saehyun is trying to lure him. But, unluckily, he died because Saehyun planned to kill you but Yoo-Ih is stopping Saehyun, but in the end Donghae was thrown on the sea and drown. Donghae wished for another life on other's body, so it was granted, he was born again in somebody, Yesung, who was being busted by Saehyun. You didn't  know that Donghae lives in Yesung's body, but you feel Donghae's presence on him.