Billy Ray Cyrus and Firerose have sparked speculation they have got engaged.
The 61-year-old singer - who split from his wife Tish Cyrus in April after 30 years - is thought to have popped the question to the Australian singer after she was spotted wearing a huge diamond ring.
A source told The Sun newspaper's Bizarre column: "Billy is happier than he has been in a long time with Firerose.
"There had been problems in his marriage for a while.
"He and Tish have been on and off for the best part of a decade, but things had been over for some time before the announcement in April."
Billy Ray and Firerose worked on single 'New Day' together last year, and the couple have been spending lots of time together lately and documenting it on social media.
Earlier this month, the 'Achy Breaky Heart' hitmaker shared a picture of the pair on Instagram.
He wrote in the caption: "Hanging out in our trailer taking a break from filming. Counting our blessings. Sending love and harmony your way."
Billy Ray and Tish - who have children Noah, 22, Braison, 28, Miley, 29, Trace, 33, and Brandi, 35, together - confirmed their split five months ago, admitting they broke up "with love in their hearts".
In a joint statement, they said: "It is after 30 years, five amazing children and a lifetime of memories, we have decided to go our separate ways - not with sadness, but with love in our hearts.
"We have grown up together, raised a family we can be so proud of, and it is now time to create our own paths.
"We will always be family and look forward to a continued and loving shared experience as friends and parents.
"We have not come to this decision lightly or quickly but with so much going on in the world, we wanted to provide some clarity and closure, so we can remain focused on what is important."
According to court documents, actress and producer Tish, 55, had filed for a separation from the musician in Tennessee a week before they confirmed their split.
Billy Ray's team declined to comment when asked about the engagement.
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