How do I know if my husband slept with someone else?

You may know that your husband may have been having an affair, but you may not be sure about it.
My website:

What you should do is check on his behavior regularly, especially if he is very secretive, and avoid being with you. If he is being unfaithful to you, then it's high time to confront him about it. Once he admits to the affair, it's time for you two to work on a solution for your marriage.

It's important that you get into the habit of asking yourself whether your husband is sleeping with other women. Once you start doing this regularly, it will become second nature and easier for you to find out if things are going well in your marriage.