Sexual jealousy, called “mate guarding” by the sociobiologists, happens when someone we love shows attention to another potential suitor or mate. Unfortunately, for others there is an almost constant and unreasonable state of jealousy. Socio-biologists think of jealousy as one of the most powerful emotions humans can feel and argue that the sexes will have different reactions to the threat of infidelity or abandonment based on different “reproductive strategies”. When jealousy gets out of control, however, it has the potential for extreme consequences. We believe that everyone should be on the lookout for warning signs of jealousy that may become extreme. This chapter talks about alcohol and sex in real life, sexual assault, and erectile dysfunction (ED).