They didn’t walk out until Cruz insulted them on a personal level.
It's more than a little like Obama and his supporters in 2008. In each case, there is a double standard for the candidate and his supporters. They and their Hope and Change are not allowed to be criticized, and they are attacked for having the audacity to criticize.
And both Trump and Obama set out to break down traditional American values and replace them with manners derived from the 1960s.
Cruz is finished as is Rubio. Just a matter of time.