Sometimes players get bored of the game. It's a fact of life.
But if they express a desire to be playing Monopoly instead, you really know you're doing something wrong.
Padmé: Jar Jar, we need to help Obi-Wan and Anakin investigate this clue.
Jar Jar: Can't we do something else?
Padmé: Like what?
Jar Jar: Play Monopoly.
GM: Um... we're roleplaying. What do you want Jar Jar to do?
Jar Jar: Jump under a bus.
GM: Jar Jar wouldn't do that.
Padmé: Sally, I thought you liked playing with us?
Jar Jar: It's a stupid childish game and you should all grow up!
R2-D2: She might have a point.
GM: Um... Shall we finish there for tonight? We'll start fresh next week.
Jar Jar: Jar Jar is stupid! I'm sick of this stupid game! I'm not playing any more!