Sophia Bush is mourning the death of her ex-boyfriend Daniel Fredinburg, who was among the casualties of Saturday's colossal Nepal earthquake.

Bush and Fredinburg reportedly split in August 2014 after a 10 month relationship because their busy schedules made the relationship "impossible to maintain."

Despite their break-up, Fredinburg, a Google executive, and Bush stayed friends.

"[Fredinburg] was one of my favorite human beings on Earth," Bush wrote on her Instagram Saturday. "He was one of the great loves of my life. He was one of my truest friends. He was an incredible brother, a brilliant engineer, and a damn good man. I'm devastated and simultaneously so deeply grateful to have known and loved him, and to have counted him as one of my tribe."

Fredinburg was in Nepal to climb Mount Everest. Before he could finish his quest he was caught in a deadly avalanche caused by the earthquake. 

"I was so looking forward to our planned download of 'all the things' when he got home, wrote Bush. "I am crushed that I will never hear that story."

Read Bush's entire tribute to Fredinburg here.