Feelings of the moment?  Which law or section if the Constitution talks about elector feelings? Always verify what you are taught.

BTW, just to be clear, electors pledge prior to the election to cast their vote according to the will of the voters. All of these electors publicly committed to cast their Electoral vote for Hillary if she won the majority of the votes (there's your democracy thing) in the state of Colorado. Because the people of the state of Colorado  (again, democracy) have determined that Colorado's electors will all be awarded to the winner of the majority of votes in the state. 

It is these 2 electors that tried to use feelings instead of honoring their prior commitment to the democratic decision of the state's voters. And the state, through the democratically elected Secretary of State, said "No". So your teacher was quite wrong. Electors are not allowed to use emotion in Colorado, they are tied to the decisions made democratically by voters of their state.