While Kelly Kelly is trying to play it off to people in the wrestling business like she wanted out, I'm told she was actually seeking a new WWE contract and they chose to cut her loose. Kelly was protected during John Cena's divorce and by many accounts, "pampered" as her affair with Cena could have been very damaging had it been brought to light during the divorce proceedings. One source says WWE was going out of their way to please her (such as allowing her to take outside appearances while under contract) and it went to her head. When it came down to negotiating a new contract, I'm told Kelly made some pretty large demands.
Once Cena's divorce was settled, Kelly Kelly went from being a "very important pawn" to irrelevant. She had reportedly become very high maintenance and the company no longer saw a reason to keep her around. I'm told Cena's preference was to no longer have her employed (because their relationship is long over) but he played no part in her departure.
I'm told Kelly really brought it on herself by playing hardball when she didn't have any leverage. One observer likened it to Chyna's WWE departure where she became easy to get rid of once she started to make large demands but had lost leverage when her relationship with Triple H ended.
Given Kelly's large price tag for independent appearances, I'm told Kelly likely didn't learn her lesson. Vince McMahon was said to be pleased with her departure as she had begun to rub him the wrong way.