There is a debate about which Meatbun between Yuwu and erha is the saddest and I'm here to share my opinion on it.
And my opinion is: they are sad differently.
Yuwu ? Sad from the beginning. Mo Xi is genuinely devastated and holding back his tears from the beginning of the story to the end. This boy is a sad boy through and through and the love story is set up to be just sad.
Erha is sad and gets sadder and by the end of the story, it's essentially devastating too. But it's definitely sadder on reread, everything that you thought was funny about Mo Ran (who is the main source of humor in the first read) at the beginning of the story just switches to devastation by the end.