In the book about motivation and personality by Abraham Harold Maslow, he found that besides basic physiological and security needs, people also have got the need for affiliation. There is no doubt, that we are social beings. Regarding to this, we perceive the absence of our friends or our beloved. This absence most likely triggers a feeling of discomfort. Thus men tries to imply actions that lead away from loneliness and isolation by, for instance getting more involved into a social group.