Howstuffworks has an interesting article on the biological and psychological differences between men and women. Some interesting excerpts:
Women’s tear ducts are also shaped a little differently from men’s, which could be either a cause or an effect of increased crying [Source: New York Times]. In addition, people who are depressed may cry four times as much as people who are not, and two-thirds of people diagnosed with depression are women [Psychology Today].
but things are more complicated, and in general there’s a good reason why women and hormones have such a bad relationship:
Studies show that, in addition to worrying more often, women may be physiologically prone to experiencing more stress. For example, the amygdala of the brain processes emotions like fear and anxiety. In men, the amygdala communicates with organs that take in and process visual information, like the visual cortex. In women, though, it communicates with parts of the brain that regulate hormones and digestion. This may mean that stress responses are more likely to cause physical symptoms in women than in men [Source: Live Science].
and to top it all off:
In addition, women’s bodies produce more stress hormones than men’s bodies do. Once a stressful event is over, women’s bodies also take longer to stop producing the hormones. This may be a cause or an effect of women’s tendency to replay stressful events in their minds and think about upsetting situations [Source: Psychology Today].
But the most interesting part is this:
In one German study, researchers showed participants images of several scenarios. The participants used a computer to describe which of the scenarios would be more upsetting. The results suggest that, across cultures, women find emotional infidelity more upsetting than sexual infidelity. Men’s responses varied across cultures, but in general they were jealous of sexual infidelity [Source: Human Nature].
Sounds like it should be OK to have sex with other women as long as you continue bringing flowers to your wife.