Kaley Cuoco officially filed for divorce from husband of 21 months, Ryan Sweeting in court on Monday.

The 29-year-old "The Big Bang Theory" star cited "irreconcilable differences" as cause of separation. According to court documents, the highest-paid TV actress and the 28-year-old tennis pro have signed a pre-nuptial agreement on spousal support and property assets in November 2013.

News about their split may have broken out last week but legal papers confirmed that they were already separated since September 3. "Kaley Cuoco and Ryan Sweeting have mutually decided to end their marriage," a rep told People Magazine on Friday. "They ask for privacy at this time. No further statement will be issued regarding this matter."

Prior to their split, another source told People that the estranged couple had been showing signs of troubled marriage. "Kaley and Ryan seem to have totally different personalities. Kaley is extremely focused and high-energy. She seems to always be working."

"On her off time, she also keeps very busy," the source said. But "over the summer, Ryan spent a lot of time at home," the source added. "He has been struggling with injuries and barely practiced tennis. He has acted very down." 

The divorce isn't surprising for the couple, though, who tied the knot on December 31, 2013 just after about five months of knowing each other.

"We met on a blind date," Couco-Sweeting previously shared on the Late Show with David Letterman. "We texted a little bit, dinner was great, and then he moved in the next day."

"I know you're all thinking, 'She's nuts!'" she added. "I swear I'm not nuts! We were throwing a New Year's Eve party anyway, and I was like, 'Let's throw a ceremony in the party and not tell anybody.'" 

Couco and Sweeting got engaged after three months of dating.