They tied the knot over Christmas last year, with both stars publicly stating their impromptu wedding was in response to the trauma of losing their home in the Malibu fires of last November.
But family and friends worry Miley Cyrus, 26, and Liam Hemsworth, 29, rushed into things too quickly, after her behaviour at the recent Met Gala raised eyebrows amongst their inner circle.
"Liam knows that Miley is a free spirit, but sometimes she goes too far," reckons a spy close to the couple, who says Miley got a tongue-lashing from her unimpressed husband after their attendance at the Gala.
"She was licking his face for the cameras on the red carpet, then grinding on people on the dance floor inside and grabbing her crotch," they say.
"He gets turned off when she acts up for the cameras. He really doesn't like that side of her, because he is the total opposite."
This was a big part of why the couple, who first met while filming the movie The Last Song in 2009, broke up in 2010 before rekindling their romance a year later.
"He felt like she turned into a different person, looking for attention," shares the insider.
Now history may be repeating itself.
"Liam is disappointed at Miley's immaturity and has been vocal about it," reveals the spy.
"After the Met Gala, he didn't talk to her for three days! She just thinks, 'Hey, you married me, you knew were you were getting into'!"
WATCH: Miley Cyrus and Liam Hemsworth at the Vanity Fair Oscars party. Story continues after video…
One source says Miley's behaviour right now could be in response to the dramatic events of last year.
"I think things happened just so fast for them, losing it all in Malibu, then the wedding," says the spy.
"I think that's one of the reasons she is being a real rebel."
According to the insider, that's caused a real strain – and Miley is reinforcing negative opinions of her that have already been formed by some close to Liam.
'Now with the way that she is acting, they feel like their suspicions [have been] confirmed,' declares the informant.
"She is just too wacky for them!"
So can the leopard change its spots? Friends think the couple may be too young to settle down, and that Miley is feeling stifled in her marriage.
"She's bored!" says a source.
"She is acting out like a teenager. [Liam] wants a wife who is ready for babies and she is like, 'Let's go to the club!'"