@Seraph_best_girl I think Maryjun knows that Vio is suffering. She just doesn't know how deeply. Right now she's doing passive things like trying to get her father to acknowledge Vio at the dinner table. I think if things continue she is going to confront her father about it.
Yulan is close to seeing what Vio really wants. Which is - to be loved. She's lived a life of neglect and abuse and she's given up on being loved. He's seeing it as "she's just tired of it all" which isn't wrong, but not quite the full picture either.
If the prince were really, really serious about being with Vio, he'd want to learn why she's changed - or better yet, just learn more about her. Period. Though she's still trying to pair him with Maryjun.