'I'm so happy to be engaged and looking forward to a life of happiness with Liam,' Cyrus says.

Sometimes on-set romances blossom into the real thing. That's clearly the case with Miley Cyrus and "Hunger Games" star Liam Hemsworth , who announced on Wednesday (June 6) that they are engaged.

"I'm so happy to be engaged and look forward to a life of happiness with Liam," Cyrus, 19, told People magazine. The couple have been dating for three years since meeting on the set of "The Last Song" in 2009. Australian actor Hemsworth, 22, Cyrus' co-star in that film, proposed to the pop country star on May 31 with a 3.5-carat diamond ring. Earlier this year the couple denied that they were planning a wedding after Cyrus was spotted with what some thought was an engagement ring.

Cyrus began dating Hemsworth shortly after ending a nine-month relationship with model Justin Gaston. It was been an up-and-down ride ever since, with a break-up in August 2010, a reconciliation and then another split later that year and a second reunion in April 2011.

In an interview with Details magazine earlier this year, Hemsworth said he tried to be professional on the set of "Last Song," but could not help falling in love with his co-star. "What happened happened, and we've been together ever since," he said. "She makes me really happy. When you start, you want to be professional, but when you're filming those scenes with someone and pretending to love them, you're not human if you don't feel something."

life is beautiful — Miley Ray Cyrus (@MileyCyrus) June 6, 2012

Early Wednesday morning Cyrus tweeted the phrase, "life is beautiful," but has not made any further comments on the engagement.

The couple will be busy in the lead up to their not-yet-scheduled nuptials, with Cyrus working on her fourth studio album and Hemsworth filming the movie "Empire State" in New Orleans. After that, he's off to co-star in the thriller "Paranoia" with Harrison Ford and Gary Oldman and then work will begin on the second "Hunger Games" installment.