To Snoop Or Not To Snoop?

Many years ago, some friends and I were discussing about infidelity and the need to know or remain in total oblivion. I vividly recall one of them begging us never to let her know if we ever catch her hubby creeping around with another woman. I was quite taken aback because by nature I am a very curious person who likes to lay all cards on the table and generally avert nasty surprises. I was quite stunned at her plea to remain in denial of the obvious, I still can't understand why some people would rather not know. 

I know for sure that I would want to know o! Just so I can know my stance and plan my life with or without the cheating spouse. Also, in this day and age, with all manners of sexually transmitted diseases being spread mostly as a result of cheating partners, why wouldn't anyone want to know if their partner is cheating from the onset in order to nip if in the bud and salvage the relationship/union?

STDs aside, I believe that when the one being cheated on knows sooner than later and brings it to light, it can also help the lust-driven cheating spouse see what he/she stands to lose if the affair isn't cut off pronto. After the lust-phase might come the love-phase so why risk the cheating spouse crossing over to that dark side when you can snoop, know and nip in the bud?

Would you snoop to ascertain or rest your fears or rather not snoop and remain in seemingly blissful denial?