"Miley is beyond happy to be engaged to Liam again," a source close to the singer tells PEOPLE. "It might seem sudden, but they have been very close for the past few months."
Over the last week, the star has been wearing the Neil Lane ring Hemsworth proposed with in 2012 (they split in late 2013).
"They just wanted to keep their relationship out of the spotlight while they figured things out," says the source. "Liam never liked how exposed his life was with Miley."
This time around, Cyrus is "making changes for their relationship to work," adds the source. "They both seem much more mature."
Source: Miley Cyrus / Instagram
The couple is planning to move back in together and are figuring out where they will be settling down.
"Miley wants to get married," says the source. "His family was very hesitant about a marriage in the past, but they really got to know Miley better when she spent time in Australia a few weeks ago. Everyone seems excited that they are back together."