The stars, who became engaged last summer (12), have rarely been spotted together in recent weeks and the separation has led to speculation they have called time on their relationship.
However, Cyrus now admits work has been keeping them apart as she has been so busy recording her new album.
She tells V magazine, "I'm not home with my boyfriend all the time. We work! He gets up to work out at six (am) and I come home around five (am) from the studio.
"Every week it's, 'Are they broken up? Because we don't see a photo of them'. I don't have time to go to Starbucks with my boyfriend every morning. I wish I did, but I don't.
"I've put this record before everything and I've never done that before. I've put too much into this record to put anything else in front of it..."
The singer/actress goes on to declare she is determined to fix the relationship and will make sure she spends plenty of quality time with Hemsworth once her album is finished.
She adds, "I'm going to change. I'm going to be different. I'm going to do what I want to do.. (But) I'd rather chill at my house and be there for the time I actually get to spend with him."