Genuine question: why do you support someone that you know openly lies to you?

Life can be complicated. I could call her out on her lies and she might apologize. She might even cry a bit. Or she might invent some excuse for her lies. Or she could get upset with me because I pretended not to know. One thing I'm sure about, it would only be a matter of time before it happened again, and next time she would be more careful to avoid getting caught.

I accidentally discovered a few years back that the mail gets censored before it makes it to the house. Officially we are debt free, unofficially there's a letter in the box right now from a lawyer because she had a credit card she didn't pay, and it got turned over to collections and she didn't pay them either, so they sued. Now how exactly she managed to keep me in the dark about that I'm not sure. So a few hours from now she'll come home and I'll ask "did we get any mail today?" and she'll say "just some sales papers and some clothes I ordered" and I'll just look the other way and smile.