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.
If you don't have peace, everything is going to feel out of place to you. You'll be agitated and frustrated. But if you find inner peace, you'll notice what irrational had hid. Maybe everything was in place and you didn't notice.