If you think about how to check a guy for loyalty, then you are probably ready for the consequences of such a decision.
Now the matter remains small: to develop a cunning plan.

The easiest way to make sure of the moral qualities of your friend is to start a left account on social networks, stick a beautiful avatar, ask to be friends with your boyfriend, and start flirting with him.

Benefits of verification of allegiance in social networks:

You will be able to act personally, without relying on someone else, so you will analyze information coming from the primary source, and not from an intermediary.
You know well the tastes, interests, and preferences of your boyfriend, so you can play the perfect girl that kindled interest in him.
This is a great way to get to know your friend better, and to hear something new about yourself - this will help strengthen your relationship, of course, if the girl passes this test of loyalty.
When creating a fake account, be very careful that he does not think that you are an annoying bot and immediately reject the friend request.

You need to be especially careful with photographs - this is the easiest way to sleep.

How to expose a cheating boyfriend using Instagram
To expose the guy in instagram dm cheating, you need to go to Instagram and go to search mode. In it, select the last tab "Places", in which you need to enter the exact location.

After choosing a location, you will see a standard post tile. After opening them, you can go to user profiles and see their stories.

On most modern smartphones, it is possible to record the story you are interested in from the screen without additional programs - the corresponding function can be hidden in the top menu bar.

Slow motion playback of the recorded video or its stop at any frame is also possible through the editor of the standard phone gallery application.

But whether it is worth spying on people in this way is another question. It is unlikely that anyone will enjoy being closely watched, even if it happens on social networks.