Relationships are built on communcation. However, in a marriage, communication takes many forms.
Yes, verbal communication is important and paramount. You need to feel comfortable to talk about anything. There should be nothing you feel guarded in saying to each other. If there is, you need to work through these.
Physical communicatuin us also important. You must learn to talk to each other through your actions and touches. Does she like to be cuddled, held, kissed, etc. Do you like to make love in the morning or night, and it turns out she likes it the other way around. I mean what tells you she wants to make love to you and you to make love to her. It doesn't stop here it goes deeper, but that is another discussion.
Mental communication, is one that is the most difficult, but is the most devastating if it is not detected early, like christa had said, this can appear at any time after the marriage has happened. I have seen it and experienced it. The eyes tell many stories.
So in a nutshell, it is comunication being the key, but it involves all forms. It is not a science, because we use these in our everyday life. What we need to do is to fine tune them for marriage.
I now have a marriage that I have been looking for my entire life. Now that I have found it. I wish this happened 30 odd years ago. Love is a wonderful thing, but it all is based on not just saying the words, but comunicating them is ways you are comfortable.