Intimate relationships play a central role in the overall human experience. Humans have a general desire to belong and to love, which is usually satisfied within an intimate relationship. These relationships involve feelings of liking or loving one or more people, romance, physical or sexual attraction ( but not always) or emotional and personal support between the members. Intimate relationships allow a social network for people to form strong emotional attachments.
Intimacy generally refers to the feeling of being in a close personal association and belonging together. It is a familiar and very close affective connection with another as a result of a bond that is formed through knowledge and experience of the other. Genuine intimacy in human relationships requires dialogue, transparency, vulnerability, and reciprocity. It does not have to be sexual in nature. It also requires honesty and trust.
I've met a lot of people on Google+ and the vast majority of them are friends, but we are not intimate in the above sense. Of the married people I have learned to trust and confide in, the number one reason they state for not being happy in their marriage is "a lack of intimacy".
I think this underscores just how important achieving and preserving real intimacy is -- in any kind of interpersonal relationship.
Robert Sternberg said, "Passion is the quickest to develop, and the quickest to fade. Intimacy develops more slowly, and commitment more gradually still." When you can achieve true intimacy with either a friend or a lover, it is something to be cherished and protected.