Their faith wears thin when the people get tired of monotonous food. Even though God is miraculously providing for them, it is not good enough. Like any leader, Moses gets tired of hearing them complain.
It’s hard to avoid complaining, even in abundance. It seems what we have is never good enough. A little more, or something a little different, seems to always be the pathway to happiness. Maybe what is needed is a little more faith and a lot better attitude.