Simply put, broken families and divorce rates are unhealthy. Open sexuality is viewed by many as a moral contagion that breaks apart society. Children from single parent homes are far more likely to encounter serious problems throughout life.
It is exceedingly more complicated than most either realize or are willing to admit.
If someone genuinely wants to understand why open sexuality is more frowned upon than violence then that person has to be open to viewpoints more elaborate than "love is love." Often however, I suspect folks aren't necessarily interested in truly understanding so much as condemning, using the "violence v/s sex" as a rhetorical weapon.
