While it is true that some people do experience immediate changes in their relationships, it's also true that, in most marriages, change takes much longer. How much longer? It depends on many factors: the severity of the problems, personalities of the spouses, length of time people have been experiencing difficulties, each spouse's level of motivation to do what it takes to make a marriage work, outside influences from extended family and friends, and the level of both partners' problem-solving skills. Every marriage is different.
But the consistent message I've gotten from those in the trenches is that patience is not only a virtue, it's an absolute necessity.