You spend years making smart financial decisions. You save aggressively, live below your means, and watch your retirement accounts grow. Then life happens. The family grows, the starter home no longer works, and suddenly your mortgage payment triples.Even when you can afford it, why does it feel like you've made a terrible mistake?This week, we answer an email from a listener who isn't really asking whether he should pay down his mortgage or save for retirement. He's asking a much deeper question: How do you adjust your financial plan when your entire financial reality changes?