It is a very difficult and challenging job to find out that who slept with your wife or not. It is even more difficult to find out hidden and secret relationships of any person especially your wife. So far your question that how could you find out whether your friend slept with your wife is a difficult one yet I will try to justify it to some extent.
First of all try to find out the business of your wife and your friend as well. You will have to become a detective to perform this job. Casually tell your wife and friend as well at the same time that you are going out of the city. Make your false programs in front of both of them so that they are deceived and if they are in love with each other or they have sexual relations, they will definitely make a program to sleep together. Then go away in their presence and try to seek out reality in a secret way. If they have such sort of relations, it will be exposed before you. Secondly give maximum chances to your wife and friend in isolation and observe them minutely in a hidden manner. I am sure by adopting these steps you will find out whether your wife sleeps with your friend or not.
First of all try to find out the business of your wife and your friend as well. You will have to become a detective to perform this job. Casually tell your wife and friend as well at the same time that you are going out of the city. Make your false programs in front of both of them so that they are deceived and if they are in love with each other or they have sexual relations, they will definitely make a program to sleep together. Then go away in their presence and try to seek out reality in a secret way. If they have such sort of relations, it will be exposed before you. Secondly give maximum chances to your wife and friend in isolation and observe them minutely in a hidden manner. I am sure by adopting these steps you will find out whether your wife sleeps with your friend or not.