Originally Posted by becreative

No its not that simple. You could terminate at B for any number of valid reasons. If the airlines thought this was not the case then they would be charging those penalties left right and center. Let us see what they do charge for... seat selection, baggage, food (buy on board), change fees, pillows, blankets, headphones (phew I am surprised they haven't started charging for seat covers yet). Rest assured if the airlines really thought that they could squeeze out more revenue because you "owe" them for a flight that you had paid for but did not use then they would go after you to make you pay. It is just that simple.