This is horrific, and becoming more and more frequent as a defence.
In a slightly different angle, I was involved in a civil case where this was ran as justification rather than defence. (Changing minor details here).
What confused proceedings was the lodging of a 50 page contract signed on each page by both parties. I have never in my life seen anything like it. This document was detailed to the extreme and ran as a tick box system. Two columns, each party had to tick which things they were agreeing to. It went further than that in that it said agree, agree even if safe word used, disagree, agree if verbal consent given at time.
She was alleging domestic abuse including sexual and him not being a safe individual to care for children. He was using this as his proof that she was compliant. It was dated the year they got together and he had one for every year of the relationship.
Those documents were gone over page by page and I'm quite sure if there had been a jury that's where they are getting these verdicts.
It took me a very, very long time to get the severity of that out my head.
Contract law clashing with everything else. Disgusting.