Have any of you created a lie that was successful because of the lack of evidence to disprove it to the point where you had to then act like the lie was truth to the person (or people) who knows you're lying anyways?

To put it into an example;

Let's say Bob is our liar. Bob has a 'friend' named George. In-between Bob and George is a girl. Let's call her Abby. Bob is a machiavellian and red pill supporter; he employs their tactics in his day-to-day activities and motives. George is our everyday average 'Joe'. Both want Abby for romantic purposes (George's motives are more pure..).

Bob lies about George to Abby, and wins her over. George on the other hand knows he's lying because Bob has admitted it to George. But, George has no evidence and therefore cannot prove that Bob is lying. Bob has become successful. However to (here's where my question comes in: have any of you gotten to this point and done this) ensure that George never gets evidence through a tape recording or anything now to subsequently fuck him [Bob he tells the lie to George as if it's the truth.

I know this sounds confusing, but it's like pretending the lie you know is a lie is fact to the person who knows it's a lie. If you understood everything above and my question, have you guys ever been in this position and done it?

Thanks.