<human>: Give me the gist of the text in a nutshell

Take for example my ex, right before i broke up with her i knew she was talking to some guy on skype and later flew to a different state to see him. Before she left i broke up with her and she was all butthurt (cheatin slut). When she wanted to be "friends" i simply stated over and over i want to know the truth. Now this guy is 36 and a ceo of a small startup, she's 17. So i basically said, "here tell me the truth about everything so i can go live my life, maybe i'll come back and be just a friend. If not I'll file a report." I told her i filed it lately and she's EXTREMELY distraught about it (obviously). The thing is i didn't and i'll ask her tomorrow or the next day to reveal the truth about a lot of things, i just like to know the truth about things. I've already moved on and i'm starting to see someone who's better in every way, but I'm a seeker of the truth....it's somewhat a problem. Yes i have mountains of evidence i haven't showed her because i'm waiting for her to tell me the truth, honestly this girl needs some extreme mental help.
<bot>: what's the psychological reason someone would lie when telling the truth results in no penalty but lying results in a severe penalty?