I was listening to an Alpha Male S video talking about how you should not wonder what your gf does and stay on your purpose, for ex: if she's going to a party, you should not wonder if she's dancing with a guy, because you know how good you are and she needs you.

Okay, so I need to understand this better. How often should we apply this and when? If your guts are telling you ''maybe, she lied to you and now she's fuckign another dude'' should you check her on this or just keep being on your purpose and maybe let her cheat on you secretly just to find out later. How can you check a girl but still not wondering if she's sucking another dude's D?