How well do you know your man??😓

so I have recently heard that my best friend's husband has cheated on her with his manager,they seemed like the perfect couple!! His always talking about her,posting things,being really in love and then that happened...Since hearing this news iv been wondering like how do you even know his faithful it kills me to doubt my husband but it's also nerve wrecking like I witness these betrayals and start doubting that no matter what you do, men will always seek!! How do I know his not doing this in his work place,erases messages before he gets home like do you ever just have peace of mind 🤦🏼‍♀️ I'm even emotional about it probably because I'm pregnant as well.