Those who are crying, this is a HAPPY ENDING. Te world where MC continued to live is a world CREATED by the Dragon for his sake, so in order to return back to him, he has to complete this timeline die and then be reunited, which they eventually did. I mean yes in THIS world he gets to die alone without his lover next to him, but remember, he was surrounded by people who loved him, like his niece. Its actually pretty sweet.