An affair. It’s something that can destroy a marriage, a family, and all the lives connected to it. And it’s something we all hope will never happen to us. But here’s the harsh reality: An estimated 53% of all people will have one or more affairs during their lifetime. And when it happens, 70% of wives and 54% of husbands don’t even know their spouses have had an affair.

Infidelity isn’t something to be ignored – it is a threat to your marriage that you need to protect against. In fact, sexual temptation can be one of the most subtle and potentially destructive threats to your marriage.

Husbands and wives: here’s something you need to know. Men and women are usually drawn into an affair differently. For men, it’s about physical attraction. They’re typically captivated by the way a woman looks. For women, the temptation is more emotional. They’re usually lured in by a man’s kindness, attentiveness or affection. But there can also be exceptions to the rule. Sometimes women are tempted by a man they consider handsome, and sometimes men are enticed by a woman who is attentive and caring.

Here’s the reality: “Falling” into adultery rarely happens. Illicit liaisons don’t just pop up out of nowhere. They grow out of something that was once innocent and harmless. And healthy marriages don’t just go bad overnight. They erode over time through neglect and disinterest.

And adultery doesn’t begin in the darkness of a hotel room, in a secluded storeroom at the office, or in someone else’s bedroom. It doesn’t even begin with the first look or word or touch. For men and women, adultery begins in the heart. That’s why it is so important to learn how to guard your heart against these kinds of threats to your marriage.

Sometimes a man or woman is drawn away by the attention and interest of someone else because their spouse isn’t paying attention to and isn’t interested in him or her. When you stop pursuing and courting your spouse, you leave your spouse’s heart unattended and vulnerable to anyone else who shows interest in him or her. But a disinterested and inattentive spouse is no excuse for a husband or wife to turn to someone else to meet his or her needs. It only makes a bad situation worse and ultimately – more painful.

When a man or woman goes to bed with someone other than his or her spouse, they’re not only acting selfishly and wounding their own soul and marriage; they’re also wounding the person they’re with, soiling that person’s marriage or the future marriage God may be preparing him or her for. The damage is incalculable.

You probably wouldn’t travel a steep, winding mountain road in your car if there weren’t guardrails for safety. Guardrails are there for a purpose: to protect you and your car from plunging over the edge. In the same way, you need to establish guardrails in your life to keep you safe from the sexual temptations you will encounter on your journey. These four guardrails will help you guard your heart and marriage from the perils and pain of unfaithfulness.