Not to say I believe that's what Jodi Arias did, as there isn't a bit of evidence for it, but...
Not to overshare, but I mentioned I was in a year and a half relationship with a Borderline Personality that I only knew was BPD after the fact.
She did exactly that. Made up a faux pregnancy, then a horrendous story of a miscarriage and this little curly-haired fetus.
Total false and vindictive mind game. And in the mind of a Borderline, all is fair when there's some punishment to be meted out. Being vindictive is how they keep score. A borderline in the throes of their illness may not be a sociopath, but very often they are just as manipulative and empty inside.
You know what, Travis may have gotten the diagnosis wrong, but the betrayal might not have been one thing. It could have just been his realization that he loved and gave the benefit of the doubt to a person who was not only incapable of reciprocating in any normal sense, but who considered all means to punish, humiliate and simply torture him for not getting her own way to be fair game.
Realizing that all this time you've been looking into the eyes of something that isn't quite human, that there's a mask that has to be pulled off, that anything that they told you that was actually true was just an oversight on their part, is betrayal enough.