While we still do not have a definite answer as to how long he has been upset with the company, we do know now that CM Punk was already contemplating a departure from WWE as early as Royal Rumble 2014. He vented to Mick Foley at the time about not being happy within the company and having trouble dealing with injuries.
Since his wedding to Maryse Ouellet is taking place later on this month, there is a very good chance that the current story line for the Miz is a way to write him off of television. Though he hasn't been penciled in for a match at Wrestlemania 30 yet, he's expected to return by then.
Miz and Maryse Ouellet are really trying to build a life together. Aside from getting married in the Bahamas in February, the couple also has been looking for a house to purchase. Since Miz has been on the road with WWE, his fiancee has been in charge of finding them a new home.