I have no idea either. I made it sound like I watch Ellen all the time. I work from home one day every week or every other week so only watch it then (it's currently on right now which made me type that). But if I ever came home early, Ellen was my show.
He left the show to work on other projects. It was his choice to leave, and he may be back on the show when his current projects finish up. He's been acting and producing films and just couldn't do both at the same time.