WHY????

Why do people change? Why do feeling fade off after a period of time? Why do people say forever when they know there isn't forever? Why men can never understand women? Why people can't stay faithful to one person? Why can people say "I love you", when they doesn't even meant it? Why do people only learn how to treasure after they had lost? Why do people often regret on what they had done? Why does love seems so simple yet so COMPLICATED? Is love suppose to be happy or is it only capable of causing people to cry?