It evolves through reciprocal self-disclosure and candour. Poor skills in developing of intimacy can lead to getting too close too quickly; struggling to find the boundary and to sustain connection; being poorly skilled as a friend, rejecting self-disclosure or even rejecting friendships and those who have them Vitalio, D. (2005) Be Your Womans Hero, not Wuss: Part 1, internet newsletter 21st April 2005.
Physical intimacy occurs in the latter but it is governed by a higher order strategy, of which the other person may not be aware. For example getting close to someone in order to get something from them or give them something.
Research by Desmond Morris, a behavioral psychologist, found that most new relationships followed 12 predictable steps on the path to sexual intimacy. Couples that rushed through the steps or skipped steps were most likely to break up.
Source: Wikipedia > Intimacy
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