I think so too- unless LE knows she was there at the house that night, and that's why she's on the witness list. Based on everything we know of his personality and habits prior to the day/night of the murders, he seemed like the kind of guy that would be chivalrous, gallant, etc- like that was how he was raised to be, the southern gentleman, the kind that would take the blame for something to protect his woman. If AP was involved in the deaths of the girls, and he loves AP or AP is pregnant, I could see them agreeing that she would just say "yes, they were arguing and I left" - she would need to be a witness to testify, and so the courts would protect her identity.