SANDRA BULLOCK was left crushed by longtime pal George Clooney’s surprise engagement to beautiful and brainy lawyer Amal Alamuddin, sources say.

“Sandra has secretly carried a torch for George for years,” revealed an insider close to the “Gravity” co-stars.

“As long as he was single, Sandra held out hope that they might get together romantically someday. But now that George is set to marry Amal, she’s a wreck.”

Another source added: “After the news came out (about George’s en­gagement), Sandra wailed to a pal, ‘That could have been me!’”

Clooney, 53, was first photographed with Beirut-born Amal – a 36-year-old international law and human rights attorney – in her London hometown in October 2013.

The couple traveled to Tanza­nia and the Seychelles in March 2014. Soon after, they were spotted together in New York City after a romantic meal at a French restaurant.

Then, on April 24, the dark-haired stunner reportedly flashed a “mas­sive” diamond sparkler while dining at the Malibu restaurant Nobu with Oscar winner Clooney and his pals, model Cindy Crawford and husband Rande Gerber.

“Hearing about that just devastated Sandy,” said the insider. “It meant that George was off the market for good. It’s hard for Sandy to wrap her mind around it.”

As The ENQUIRER reported, the “Blind Side” Oscar win­ner, 49, and Clooney seemed almost inseparable at the Venice Film Festival in August 2013, mugging for cameras, sharing private jokes and taking in the sights together.

And Clooney – notorious for dating a string of lovely ladies – gushed over Sandra at the New York premiere of “Gravity” last October, saying: “She looks beautiful, doesn’t she?”

But that didn’t translate into a ro­mance, and this isn’t the first time that Sandra has been distraught over a potential hubby being tak­en off the market.

Sandra was romantically linked to her “The Proposal” co-star Ryan Reynolds after they spent time together in Wyoming in August 2011 – and although Sandra denied they were dating, sources said she was crushed when he wed actress Blake Lively the following year.

And in 2012, sources told us that Sandra was in tears when Matthew McConaughey – whom she dated in the 1990s and hooked up with again in 2003 – walked the aisle with his baby mama Camila Alves.

Meanwhile, Sandra was thrilled when her adopted son Louis, 4, bonded with Clooney while filming “Gravity.”

“My son thinks he’s a very cool dude,” she noted in September 2013.

Now insiders say Sandra – who hasn’t had a serious relationship since divorcing cheating bad boy Jesse James – is crestfallen that Clooney will never be a like a father to Louis.

But if it’s any consolation, Clooney apparently has no plans to start a family.

“Before he popped the question, George made Amal agree not to have any kids,” confided a source.

“She and George want to continue to travel and work, and they both believe that would be impossible with a child in tow.”