The tennis player was reportedly prescribed painkillers after back surgery last year.
A source told Us Weekly (via Daily Mail), "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."
Another source added, "Kaley told friends doctors prescribed something that he was taking too much of. That is when it went downhill again."
The mag reported that Ryan had promised to go to rehab in Boston, but he was too late with his decision. Cuoco pulled the plug on the marriage after they were unable to overcome their problems. An insider said, "She couldn't fix him. He wasn't the man she thought he was."
Sweeting has had a bad history with pills — he was arrested for DUI and possession of a drug without a prescription in 2006.
After the arrest, he said in a statement, "I'm taking full responsibility for my actions. I realize what I did reflected on the school, my teammates and my coaches. I want to do whatever it takes to remain a Gator."
"Extra" has reached out to Sweeting's reps for comment on the story, but have yet to hear back.