You see, say SH was entirely innocent and had no idea of the killing or of the dismembering - if that was me, I would try to work out how it could have happened without me knowing a thing. I would look back over every detail of what must have happened - being at the house when Becky was killed, how long I really was outside, what I heard, how NM behaved straight afterwards and for the rest of the day and evening, how he had managed to do all that sawing and hours and hours of wrapping and use of cat litter, how he had convinced me we had needed 3 rolls of clingfilm and rolls and rolls of tape and bags and sacks, then even more the following day, how there were more and more cases and bags appearing in the house (from the loft?) and being filled up, how my shower curtains and bath mat had disappeared, how he had convinced me the car was playing up and needed to be left at my Mum's house even though we had driven there in it with no problems, how we had to be out on 23rd and say we had planned a meal out with my parents when I knew we had already eaten at McDonalds and there was no reason for not letting the police look inside my house - I only had a broken toilet after all,... do you know what I could go on but I won't. I would go over all these things in absolute disbelief and say how could he have pulled all of this off without my knowledge or suspecting a thing? What was in those bags that had to be got rid of in the dead of night? etc. etc.
I wouldn't just sit there and say I didn't know him at all. I wasn't even safe with him and I shared a bed with him. He has either lost his marbles or he is whatever she described him as. Her reactions are just wrong and so staged.
Even the first interview where she says she went outside for 15-20 minutes. Why does she give herself more time than it takes to actually smoke a cigarette, it was raining and if you needed a smoke you would go out, smoke it and get back inside as quickly as possible - 10 mins max. Nothing stacks up with her. She had her story ready from the word go.
I think anyone who can't see it needs to re-tune their BS detector.