Is foreplay sinful for an unmarried couple?
Yes. As quoted in the Catechism, “every species of immodesty and impurity are included in this prohibition of adultery.” This would include touching, and even long kisses (if they cause great temptation–and they generally do). The easiest way to discern is this: if you normally feel yourself getting aroused in that situation, then you’ve gone to far and have sinned. Of course, sometimes we are easily aroused because of moods, and if we do something innocent, and it arouses us, that would not count as a sin–so long as we stop there.
