According to recent research published by Dr. Noam Sobel at the Weizmann Institute in Israel, our tears are filled with chemical signals meant to influence the behavior of others. During the experiment, Sobel and his colleagues had men sniff a vial of a woman’s tears. Their bodies responded in a variety of ways, but most notable were testosterone levels and descriptions of arousal.

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According to the article, the tears send a sort of “not tonight” signal from the women to their male partners. However, there are questions about what other signals the tears could represent. Some suggested that tears could reduce male aggression when women are emotionally stressed.
I’m just gonna go ahead and stick with the notion that when your lady is crying, you should just go straight to the cuddling.