How you ever thoughts about just why Jesus said that when a man looks at another woman with lust, he already done it in his heart?
I think that it’s because by doing this he has already became unfaithful to his own wife. People cheat when they don’t care enough. I remember reading of a survey that asked married people to see how many would cheat on their spouses if they knew that their spouses would never find out. I don’t remember the exact percentage of those who said that they would, but I do remember that it was a significant amount. (I’ll look more into the actual contents of this.) Perhaps these are the same people who love or at least claim to love their spouses with all their hearts and who would never intentionally hurt them. One thing that these people don’t know however is that the second they do it - cheat, they hurt them even before those spouses know about it. Think about this:
As soon as a spouse finds out about the unfaithfulness, he or she at once gets their heart broken, is dumbfounded, is shocked, and pain fills their body. But doesn’t it kind of not make sense that the spouse feels this way only after he or she finds out the truth about the act? I think that the pain was there as soon as the act was committed, it just came to life when it was known. The person did not get upset that he knew about it, but that it happened at all.

My Pastor once told me that when a spouse gets cheated on, he or she can tell even when they are hugging. It’s almost like a human instinct. Maybe not everyone can tell, but I think most people do. Maybe they feel it, but don’t even know what they are feeling, how to describe it. So what exactly happens when infidelity occurs in a marriage? The cheating spouse might be unsatisfied with the other one, might be angry, might feel defeated in a conflict, so he or she just goes for it, with the thought of only their life, their body, their feelings. They see the moment, and the moment is so real to them. Their feelings and their pain is so real to them, so they seek for consolation. Their desire is so real to them, so they seek for the pleasure. It’s in their hands, it’s right there in front of them. They dive into it. But what they don’t know is that the minute they do that, in their own heads and especially in the act, they actually form a separation with their spouse, and break their bond. It’s as if they delicately cut through their conjoined oneness. They are still one, but the cheating spouse tries to bring somebody else right in between that unity, so it almost has no choice but to rip. How can it not!? That’s why almost all society everywhere looks so down upon it, because it is not just betrayal, but abuse.

Faithfulness is a virtue, let us all be faithful.