So your significant other is suddenly acting very differently. He is coming home later than usual or she no longer wants sex. Something’s wrong, but you don’t know why. Is your partner cheating on you?

While there is no sure-fire way to know definitively if you are being cheated on, here’s a simple technique to use to give you a better idea.

First, what not to do:

1. Don’t ask directly- You might have your suspicions and you might be right. But asking your lover directly if they are cheating on you will only put them on the defensive and it’s not like they’ll tell you the truth anyway, right? The only thing this will produce is a fight since your emotions are running high. Also, since they now know that you suspect, they will do a better job of covering their tracks in the future.

2. Don’t act possessive or jealous- Your natural inclination may be to constantly ask what they are doing and monitor their activities. In the end, it will only create resentment. People are turned off by a jealous partner and they don’t like to be told what to do. So, if you do this, you may drive your partner to want to cheat or leave you even if they aren’t doing so right now.

Here’s what you CAN do:

Ask an innocent question that would trip them up if they are lying.

Let’s say your partner comes home late. Act nonchalant and ask why they are late. Let’s say they claim that traffic was particularly bad. This is an opportunity for you to find out some information. The following technique is very simple and elegant, yet very powerful.

Make something up and act as if it is true in order to gauge your lover’s reaction.

For example, in the above situation, your lover tells you that they are late because of bad traffic. Your next sentence would be “Yes, I heard there was a big car crash on West St (or whatever street).” This statement is probably false, but that doesn’t matter. What matters is the reaction it elicits. If your partner is lying, they will admit that they were unaware of the accident and the traffic jam was in another part of town. If they are lying, their first reaction will be to assume that you know what you’re talking about and to use your statement as an alibi. You’ll hear something like, “Yes, there was a crash there. That explains the traffic.”

In other words, a liar will eagerly agree with your false statement in order to save face.

That’s one technique you can use. There are many others, but the key is to remember to not attack or confront your partner with your doubts, since it won’t answer your questions and only lead to problems.