What is secret of  long lasting relationship?

It is another Sunday evening when my best friend and  I were discussing random stuff when we came across this topic. She’s in a four year relationship and still going strong, while I on the other hand is the group resident proud single member and advocate the women power J

Our answer is actually connected, she said that both of you should have the same topak or in much understandable term, you should be in the same wave length of understanding. She doesn't mean you think alike, or be in the same kind, but it's more about how you can understand each other’s thought and action.

My answer is simple, it’s all about in the communication.

I think it is connected because most of the time, you cannot communicate well with someone who cannot see your point of view, and misunderstanding often causes of mis-communication. We maybe too young to said this word, and I may be too inexperience but we don’t need much wisdom to understand simple things and we think that relationship is pretty simple, only if you are not to complicated to deal with it.

But this questions have different answers, you, what do you think is the secret?

If this isn't too much, I would love to hear your answer ^^