Actions produce related consequences. So, lustful action can only produce related consequences, such as more lust, anger, dissatisfaction, despair, pain, etc. Lust cannot create love, patience, acceptance, serenity, happiness, etc. Therefore, the lustful person, by acting with lust, constantly increases their suffering and dissatisfaction, which causes them to spread those negative values to others. Negative values are very contagious, and spread very easily. Naturally, the people closest to the infected person will be affected the most.
Of course, becoming angry with such a person only adds fuel to the fire. To help someone who is infected with negativity requires the application of superior values.
Study this lecture:
http://gnosticteachings.org/courses/meditation-without-exertion/1676-ethics.html