the unknowing of everything/anything? ergo, Let go and be at peace...

[SoonHei]

was listening to an audio tape of byron katie and in it, she was teaching a questioner by answering her inquiry repeatedly with "can you know for sure" or "can you really know?" or "how do you know that's true"

is this what other teachers/gurus mean by ultimately realizing that we do not know anything?

like if i think my gf has some issue with me or maybe doing something which i may not like - can i really know this is the case? until i see it with my eyes? or get a physical/visual proof of what i suspect to be true... until that happens, it's all just a thought or assumption which i "cannot know for sure" or "have no way of knowing if it's true" ?

is that the solution to all/most of our problems... that we cannot know? and therefore, we should let go and not suffer the thought and deal with it when it happens to confirm itself infront of us?

one thing about this is though what if someone suspected because there were "signs" or "symptopms" that their partner maybe cheating... but since they "cannot know for sure" they just choose not to investigate or worry... all the while the partner was infact cheating behind their back and due to the fact their partner never bothered to check up on them or try n catch them in the act or confront them - the cheating partner got away with it...

am i generalizing here too much?
does that "we cannot know" theory to let-go and see thru the issue only apply to very direct thought issues only and not to the issues of trust/cheating or something else?