Trace Cyrus says his sister Miley and her husband Liam Hemsworth have an "unbreakable bond".
The 'Wrecking Ball' hitmaker and the 'Isn't It Romantic' star - who tied the knot in secret in December - first met on the set of 'The Last Song' in 2009, when Miley was 16, and the singer's eldest brother says the key to their long-standing relationship is the fact that they are both so "chill and down to earth".
Asked why they are the "perfect match" for one another, the 30-year-old star told Hollywood Life: "I think just trial and error. "They've been together since she was 16.
"It's hard to break that bond.
"From an outsiders perspective, I've met them both, obviously.
"She's just so cool and chill and down to earth and I feel like he's like that too.
"They just fit perfectly together.
"They're both just so cool and so nice and just down to earth people."
Despite sources suggesting Miley, 26, and Liam, 29, are keen to become parents, Trace recently claimed they are not looking to start a family just yet, as his sister has "so much ambition" career wise.
When asked if he could become an uncle soon, he replied: "No. She has no desire.
"I think she has so much ambition to do so much more in her career even though she's done so much. It's just not the time for her.
"She has so much time to decide that. She hasn't even hit her dirty 30 yet."
Meanwhile, Liam is happier than ever after the pair wed in Nashville, Tennessee.
He said: "We've been through so much together over the last 10 years, so [I] felt like it was time. I feel really happy and really fortunate to be with such a great person.
"It was a really special day as it was pretty much just immediate family."