Many people believe intimacy to mean sex but it is not. Some couples who are unable to feel close or vulnerable to one another may feel they need to be physical to feel close to one another. However that only creates a temporary feeling of closeness. Prolonged closeness between two people comes from emotional intimacy which is a feeling of being able to be open and vulnerable.
A lack of intimacy between two people often feels like there is a great distance between the two people. Lack of intimacy can result in boredom, being defensive, arguments, frustration and a general lack of communication.