Nothing hurts a man more than finding out that his woman is cheating. That is why a man would be willing to invest heavily into a private investigator or surveillance techniques just to catch a cheater. One fact that remains is that it is very difficult to catch a lady in the act. I am, however, intrigued at the few chaps out there who manage to catch a cheater.
But how did they do it?

Have you ever busted a cheater?

Do you know a friend who has?

If yes, how did it happen?

Help a brother ...

To catch your cheating partner, follow them if you really sure that she is cheating, confirm it and confront him or her.

Just trust your feeling.  But honestly for me, no need for me to catch her.  I will let her do what ever she wants.  Even I have some info about the cheating, I will let her to do that. let her be confused about that, and let her tell you about the truth and laugh at her, because you already know everything.

That's actually smart. It frees you from obsessing over details and stuff. You simply let stuff happen and wait for them to tell you. I can see this working for those who have a bit of conscience left in them. But liars will probably deny this to the end. 

Honestly, it is really hard to catch a cheater either a man or a woman. A cheater will always be a cheater and will definitely find a way to hide its cheating activities. Therefore, no matter what you do, having a cheater partner is not healthy so it's better to let her go. Just let her do whatever she wants to do and basically time will come those cheating activities she made will burst into her face. Make sure that when that time comes, you are fully ready to end everything between you and her.