With just skimming the other replies--
if it is a financial hardship on the family, then yes, it would have to stop. If it causing both of you stress and he wanted to quit then yes, it would stop.
I'm all for fulfilling commitments and exposing children to different activitis but sometimes less stress and more money to put somewhere else make everyone happy.
We recently went thru part of this with viola lessons. Ds was frustrated and every week was a battle. He was stressed, we were stressed and his private lesson teacher was not a good match(and the only one available for lessons).
So standing back and realizing that ds had very little talent in the way of playing a viola and was getting stressed out over something that didn't need to cause stress, we allowed him to quit. I thought we would regret the decision but we haven't. Music is not where his strengths and talents are. It's so much easier to encourage him where he does soar than trying to make something happen.