'Final Nail In The Coffin!' Liam Filed Divorce Papers Due To Miley's Humiliating Fling

He'd had enough!

RadarOnline.com has exclusively learned Liam Hemsworth decided to officially file for divorce from Miley Cyrus because she blindsided him with her same-sex fling.

According to a source, the actor, 29, wanted to keep problems with his singer wife, 26, private, and he decided "to take a break and see if anything could change.”

“Liam wanted to leave,” explained the source, “but he was hanging on by a thread hoping Miley would understand where he was coming from.”

Instead, the "heartbroken" actor was in for a rude awakening.

“A few months into their break, she is seen getting intimate with another person,” said the source of Cyrus’ very public make-out session with Brody Jenner’s ex, Kaitlynn Carter, 30, while the two women recently vacationed together in Italy.

“That is not something you do when you care about a person, let alone your husband who you are legally married to!"

The source explained the hookup was the last straw for the Hunger Games star.

“So, for Liam, that was the final nail in the coffin,” said the source. "He wants to put all of this behind him, move on, and find a fresh start."

As RadarOnline.com previously reported, Hemsworth officially filed for divorce from Cyrus on August 21 in Los Angeles.

He cited "irreconcilable differences" as the reason for the split, and noted a prenuptial agreement indicated how both parties plan to divide their assets.