After the second season of Star Trek: The Next Generation was over, Wil Wheaton had an opportunity that could have really advanced his career— to be in Miloš Forman's film, "Valmont.' The first couple of episodes of season three of The Next Generation were going to be filmed out of order so Wheaton didn't think there would be an issue...except a producer told his agent that the first episode of the third season was going to have an important scene between Wil Wheaton's character, Wesley Crusher, and his character's mother, Dr. Beverly Crusher (Gates McFadden). Supposedly the scene would have really moved the relationship forward.
When Wheaton returned to the set of The Next Generation, he discovered that the scene the producer mentioned wasn't only absent from the first script, so was Wesley Crusher. And he felt betrayed. Wheaton shared more about the story in "The Fifty-Year Mission: The Next 25 Years: From The Next Generation to J. J. Abrams," edited by Mark A. Altman and Edward Gross.
"I was really upset, because I was excited to have the opportunity to work with this amazing director in an amazing movie and in an amazing role that I thought really would have solidified my credentials as a young actor. I was really disappointed. A few days before we began production on that season of Next Generation, this producer wrote me out of the script entirely, and it was appalling to me. The message was very clear — we own you — and it was a move to sabotage my career.- Wil Wheaton
What's worse is that co-star Marina Sirtis confirmed later that the producers were concerned that the movie would have led Wheaton to be a star, and it would have been harder for them to deal with him. So they chose to lie which led Wheaton deciding to make for the exit.
"Years later, Marina Sirtis told me that they knew that if I had done this film, I would have been a movie star, and it would have been harder for them to deal with me. I felt so betrayed by that, and I was, like, F*** you guys, I am now doing anything I can to get off this show. Because I can't believe you would treat another person like that. That led me to wanting to leave Next Generation.- Wil Wheaton
And leave he did. Wheaton's last episode aired in season four of the series, and even though he was betrayed by one producer, that hasn't stopped him from being a part of the Star Trek family. Wheaton currently hosts The Ready Room, an aftershow that discusses new episodes of Trek.