The popular series of Friends finished because the actor's and actress's of the show asked for too much money, I think 5 grand per episode, so they shut down, a shame, I liked Friends!
I don't know if the actor's demanding really outrageous fees is true but I can't believe they would be that stupid.
But Courtney Cox was obviously pregnant in the last few episodes, very evidently in the last episode. She gave birth about a month after the series ended. She was the one female character that couldn't get pregnant. Did this contribute?