Life would be unbearable if everything stayed the same because human beings find situations that are fixed and predictable very hard to tolerate. Even in small matters, we become uneasy if we feel there is no end in sight. I know of couples who live harmoniously together for ten years then marry and are divorced within a year. As soon as they feel bound to each other for the rest of their lives, they begin to fight. Impermanence removes our reasons for quarrelling with each other. Arguments only break out if we imagine that our relationships are endless. When we appreciate that our time with our families, partners, and friends may be shorter than we think, we get on better with each other. Awareness of impermanence gives us extraordinary inner strength and resilience.
--from Mind Training by Ringu Tulku, edited by B.M. Shaughnessy, published by Snow Lion Publications