“Do you believe you still did something wrong, without being aware of it?”

I can’t think of anything which could have led to this. Neither of them communicated much if anything so it leads me to believe it was just an excuse. It is more than obvious that both of them seriously lack personal accountability.
When their conflict started, it was instigated by him and constantly fueled by her, yet the responsibility of solving it was placed on my shoulders. In the end, not only I was blamed for not solving “properly” something which wasn’t of my making, but also became the scapegoat for her betrayal and his vitriol towards me.

“To whom was she absolutely loyal and caring, no matter what?”

To me of course.