"To the Ancients, Friendship seemed the happiest and most fully human of all loves; the crown of life and the school of virtue. The modern world, in comparison, ignores it. We admit of course that besides a wife and family a man needs a few 'friends'. But the very tone of the admission, and the sort of acquaintanceships which those who make it would describe as 'friendships', show clearly that what they are talking about has very little to do with that Philia which Aristotle classified among the virtues or that Amicitia on which Cicero wrote a book."

C.S. Lewis

The intense emotional and affective relationships described in the past as "non-sexual" cannot be said to exist today: modern heterosexual men can be buddies, but unless drunk they cannot touch each other, or regularly sleep together. They cannot affirm that an emotional affective relationship with another man is the centrally important relationship in their lives. It is not going too far, is it, to claim that friendship – if used to translate Greek philia or Latin amicitia – hardly exists among heterosexual men in modern Western society."

Paul Hasell (interesting, he attributes it to Homosexuality)

A number of colloquial terms have been used to describe friendship and the context in which a friendship is fostered. These are briefly described below.
A friend who supports others only when it is easy and convenient to do so is called a "fair-weather friend".
A friend who sticks by you through thick and thin is a "true friend".
A friend with whom you are sexually intimate but don't consider yourself to be dating is said to be a "casual relationship". This is also referred to as being "friends with benefits".
A "best friend" is a friend to whom one feels closest (the relationship normally having to be reciprocal). A best friend may be of the same sex or of the opposite sex.

"No one has greater love than this, to lay down one's life for one's friends."(John 15:13)