既然講了Relationship與Friendship，那就來說說... 什麼是友情？什麼是親密關係？以下許多文字引自 wikipedia。

Friendship / 友誼

Friendship is a term used to denote co-operative and supportive behavior between two or more humans. This article focuses on the notion specific to interpersonal relationships. In this sense, the term connotes a relationship which involves mutual knowledge, esteem, and affection along with a degree of rendering service to friends in times of need or crisis. Friends will welcome each other's company and exhibit loyalty towards each other, often to the point of altruism. Their tastes will usually be similar and may converge, and they will share enjoyable activities. They will also engage in mutually helping behavior, such as exchange of advice and the sharing of hardship. A friend is someone who may often demonstrate reciprocating and reflective behaviors. Yet for many, friendship is nothing more than the trust that someone or something will not harm them. Value that is found in friendships is often the result of a friend demonstrating on a consistent basis:

• the tendency to desire what is best for the other,
• sympathy and empathy,
• honesty, perhaps in situations where it may be difficult for others to speak the truth, especially in terms of pointing out the perceived faults of one's counterpart
• mutual understanding.

In a comparison of personal relationships, friendship is considered to be closer than association, although there is a range of degrees of intimacy in both friendships and associations. Friendship and association can be thought of as spanning across the same continuum. The study of friendship is included in sociology, anthropology, philosophy, and zoology. Various theories of friendship have been proposed, among which are social psychology, social exchange theory, equity theory, relational dialectics, and attachment styles.

Intimate Relationship / 親密關係

An intimate relationship is a particularly close interpersonal relationship. It is a relationship in which the participants know or trust one another very well or are confidants of one another, or a relationship in which there is physical or emotional intimacy.

Physical intimacy is characterized by romantic or passionate love and attachment, or sexual activity.

Physical and emotional intimacy / 肢體與情感親密

Some believe love is an important factor in physical and emotional intimate relationships. Though the term is notoriously difficult to define, any thoughtful inquiry into the subject will show it to be qualitatively, not only quantitatively, different than liking, and the difference is not merely in the presence or absence of sexual attraction. According to one analysis,needed love in relationships is divided into two types: passionate and companionate. Passionate love is intense longing, and is often accompanied by physiological arousal (shortness of breath, rapid heart rate). Companionate love is affection and a feeling of intimacy and is not necessarily accompanied by physiological arousal.

如果親密關係沒有建立在友誼上，那麼肢體上的親密(intimate, not close)應該是很奇怪。反過來，除去了physical and emotional intimacy，為甚麼連friendship都得跟著消失了呢？