Miley Cyrus and Liam Hemsworth are engaged to be married after three years of dating, representatives for the Hollywood couple confirmed to People.com. Cyrus, 19, began dating Australian actor Hemsworth, 22, when they co-starred in the big-screen romance \"The Last Song\" in 2009. People.com said Hemsworth proposed to the pop singer May 31. \"I\'m so happy to be engaged and look forward to a life of happiness with Liam,\" Cyrus told the celebrity magazine.