In related to my other thread 
Sexual Jealousy (A Survey)
From the
Sociobiological Perspective
Taking from my text-book,
From a functional perspective, the greatest cost to a male would
be loss of paternity. Suppose a female is fertilized by a male
other than the partner and the partner then invests time and energy
in supporting the female during pregnancy and afterwards. Of
course, the male is unaware that these are genes other than his own
that he is helping to propagate. This would represent a serious cost in terms
of his reproductive sucess.
For the female, the situation is different. If a male fertilizes
another female, in itself this need have little cost to the first
female partner. However, what could have prove costly to the female
partner is the males emotional attachment to another female, which
could deny her support in bringing up children. Therefore,
psychologists adopting an evolutionary perspective
suggest that, on a causal level analysis, the trigger stimuli of
jealousy for males will be related to sexual behaviour as such,
whereas for females the trigger stimuli will tend to be biased
towards cues predictive loss of
commitment and investment in the bond. (Stevens,
p68.)
References
Stevens, R. (1996), Understanding The Self, The Open University,
Walton Hall, Milton Keynes MK7 6AA
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What do you think? 
