“You have heard that it was said, ‘You shall not commit adultery’; but I say to you that everyone who looks at a woman with lust for her has already committed adultery with her in his heart.” Matthew 5:27-28 NASB.

The ball of purity drops and touches the ground when one’s heart being enticed by the thought of having sex with someone they are not married to. So, purity or immorality is not all about a physical action but a condition of one’s heart.