No. They deserved a better ending and dying in the sea wasn't it. I'm sorry you think the epilogue ruined the manhwa for you, but for me it was everything i could've asked for. When I first finished reading this story, i was depressed for days. I thought I'd never read it ever again. But the reincarnation changed that; I now can reread it knowing that they'll find each other again and will be happy.
That's what I think the epilogue was for, some readers found it more comforting to have a happy ending as the previous ending was really heartbreaking. It's nice to have an epilogue with a happy ending, I just think that some people also like having bitter-sweet stories that aren't necessarily happy. (▰˘◡˘▰)
unpopular opinion: the epilogue shouldnt have happened. they shouldve died and it shouldve been the end of the story. with the epilogue, the peak of the series lost its meaning. happy endings arent always the best way to end a story.