The 17-year-old - Miley turns 18 on November 23 - has taken the news of her parents' impending divorce hard, and now blames herself for their marital problems, website Popeater reports.
"Both parents have been equally involved in making their daughter a superstar. And now that they have achieved their goal they have nothing to work towards anymore and nothing to keep them together," a source said.
"Every marriage struggles when a child leaves home and the relationship gets re-examined, but add on top of that that every second of the past decade Billy Ray and Tish have spent building a star together, they have forgotten to make time for each other. It's heartbreaking.
"You would think that someone like Miley has everything in the world, but I guarantee she would give it all up in a second if it kept her family together. I'm sure when she blows out her birthday candles in a few weeks her wish will be for mum and dad, not her career."