It is common for people involved in adultery to "rewrite history" of their marriage to justify their thoughts and then actions. And if is involved then it could take up to 24 months for the "brain fog" to lift. (Depending on the betrayers recovery)
Always true. But some people choose to believe deceit so that it suits what they want. Which means they are living in denial from the beginning and that the relationship will continue to be built on lies. Always be there for them when the truth comes out.