Second to the one toward theft is the pull toward promiscuity (as we’d pointed out). But while theft is never justifiable, appropriate marital relations are holy and obligatory, so there’s the rub.
The point is that some subtler, seemingly “harmless” forms of promiscuity are to be avoided, aside from out-and-out licentiousness. For we’d been warned to not “come close to uncovering nakedness” (Leviticus 18:6), not to just avoid the obvious.
And so we’re to steer clear of making physical contact with non-family members of the opposite sex by not hugging, kissing, or making other such suggestive contact with them. For as it’s written, “Those who join hands for wrongful ends will not escape with impunity (Proverbs 11:21).
We’re to not stare at them licentiously (see Avodah Zara 20a), to engage in the sort of idle chit-chat that often carries a hint of indiscretion (see Pirkei Avot 1:5), men aren’t to set out to listen to women singing according to our ethic (see Berachot 24a) as music comes from deep within and often bestirs the male heart, and we aren’t to visualize them in our minds (see Avodah Zara 20b and Yoma 29a).
Ramchal makes a cogent point here. He says, “if someone comes to confound you by saying that when the Torah speaks against ‘profanity’ it’s actually only doing that to frighten and draw a person away from the actual sin (of out and out adultery), and that in fact the prohibition is for the more hot-blooded type of person who might be brought to desire” by the latter sorts of prohibitions. But we’re to know, he underscores, that that’s simply a rationalization; for the sort of mistakes that those of us seeking “innocence” want to avoid happen indeed, and they often come about in the most “innocent” of ways.