But I disagree, philosophically, with all the people who avoid uncomfortable issues because they are 'love busters. Many people ended up in affairs because they couldn't communicate, and keeping your own doubts a complete secret seems to me to contribute to the problem, rather than alleviate it. Last September a woman from Indiana called our house, they'd been chatting up a storm for 3 months. About your question, I have let things go at times when I know my H is lying. I hate for him to think I'm that stupid at times to believe his crap.
People grow through experience if they meet life honestly and courageously.
This is how character is built. I agree with the others here. She won't listen anyway. Just to put in my two cents, I asked my stbx if it bothered her that she had spent months lying about pretty much everything. No working with that one.