Why Can't Anger Simply Be Held Inside?

I was watching a broadcast yesterday of a very open and honest couple who described some of the marriage problems they had overcome. Determined to be the 'good little wife' and not to repeat the mistakes of her aggressive father, the wife, who we shall call Sally had taken to holding all her anger inside. Sally never contradicted her husband, never nagged and never did anything to disturb the peace. However, many issues arose which were left unresolved and Sally's anger eventually erupted into violence - the very thing Sally had been so desperately trying to avoid!

What is discouragement?

Over the last few weeks I've felt alive and raring to go over a new goal/project/life change that I had been anticipating. I spent night & day researching this new area of interest pouring over the Internet, dreaming about the future and imagining every nook & detail about everything it would involve. Then two days ago I received an email from a joint partner in this project indicating that I wasn't showing enough enthusiasm or commitment to this life-changing endeavour, after struggling through my emotional response for two days I came to a point of emotional collapse about it all today, I had no feeling, emotion or desire to continue at all. What had happened and how did something which had set me on fire draw a complete blank the next day?