Sexual advances can be sexy or threatening. Emotions matter. Sex is the act that brings new people into the world, and though we have contraception and sex without reproduction, that need to feel loved is hardwired into our biology - especially the biology of women. Pregnancy and child rearing is a commitment of years and only strong emotional bonds have through evolutionary time afforded women and children any kind of longterm protection. So, in as much as modern society has given us sex as "playtime," we would do well to remember that we are creatures of our biology and respect that.