Actress Kaley Cuoco gushed about her amazing relationship with husband Ryan Sweeting during an appearance on "Watch What Happens Live" with host Andy Cohen on Sept. 20. Five days later, the couple announced that they were getting a divorce.

So, what happened?

Sweeting was forced to end her 21-month marriage to the Tennis pro because of his addiction to painkillers, according to the Daily Mail. A source claimed that Sweeting's personal struggle "turned their marriage into a nightmare," and Cuoco could no longer tolerate his addiction because "he couldn't make the commitment to get sober."

"She supported him but she said he couldn't make the commitment to get sober. He'd tell her he was working on it and instead go get wasted," a source close to the "Big Bang Theory" star told Us Weekly. Adding that the couple's "biggest blowouts" taking place over his sobriety.

Sweeting's painkillers were allegedly prescribed after he underwent surgery on his back last year, but the athlete has "developed a dependency on painkillers." The insider said that the 29-year-old actress "told friends (that) doctors prescribed something that he was taking too much of. That is when it went downhill again."

Sweeting, 28, who was arrested for DUI and possession of a drug with the intent to sell in 2006, reportedly tried to save his marriage by promising to check into rehab, but Cuoco was ready to walk away. The actress is reportedly "devastated" that her marriage is ending and has "sworn off dating." 

"She didn't want to get divorced but felt she had no choice," the source said. "She couldn't fix him. He wasn't the man she thought he was. She couldn't take his ups and downs. He'd lash out at her."

The two tied the knot in December 2013, only six months after they began dating. Sweeting was reportedly sober during his lavish New Year's Eve wedding ceremony. Cuoco filed for divorce from Sweeting on Sept. 25, citing the "irreconcilable differences."

"Kaley Cuoco and Ryan Sweeting have mutually decided to end their marriage," their joint statement read. "They ask for privacy at this time. No further statement will be issued regarding this matter."

The couple signed a prenuptial agreement one month before their marriage. According to the agreement, since they do not have any children together, they are assured a quick divorce.