Cyrus and Carter are yet to comment on their affair, but the pair and their exes were once a happy foursome of friends.
Carter has liked an Instagram post from a fan showing her support for the pair by saying the criticism aimed at her and Cyrus was unfair.
"Just wanted to let u know that u don't deserve all this hate from people who claim to be Miley's 'fans'!" the post reads. " U and Miley have every right to do what ever u want! If u make Miley happy then I like u! Miley's happiness and mental health is all that matters to me!"
Miley yesterday received support from her sister Brandi, who was sighted hanging out with her and Carter during their vacation in Italy.
"It's not my business to talk about and it's nothing anything of mine to tell," Brandi said on the latest episode of her Your Favourite Thing podcast with Wells Adams.
"There's nothing I can really say. I just, I'm here for her, obviously, and I've been spending a lot of time with her.
"When she's ready to talk about it or whatever, then she will."
A statement released by Cyrus' rep over the weekend confirmed her split from Hemsworth before Miley alluded to the changes in life in her own Instagram post.
"Don't fight evolution, because you will never win," she wrote. "Like the mountain I am standing on top of, which was once under water, connected with Africa, change is inevitable."