Actor Jim Parsons is finally opening up about the real reason why he left the “The Big Bang Theory” last year and it’s actually kind of dark and heartbreaking.Parsons played Sheldon Cooper on the hit sit-com for more than a decade, eventually raking in $1 million per episode, and making him one of the highest-paid actors on TV.In an appearance on “David Tennant Does a Podcast With…” the 47-year-old explains exactly why he chose to walk away from such an enormous annual paycheck.Parson explains that he started growing tired of the show after about ten years in and says his first suspicion “that was going to be it” struck him after he signed his contract to continue starring in Seasons 11 and 12.