Oh and I do have a question. In my sitch, I was plenty adventurous and kept my W engaged in doing different and exciting things. However she would just say no or not interested. When I asked what she wanted to do she'd say "don't know". or "up to you". So I don't know what you mean about the "boring" part. It was her choice to not participate and it wasn't from lack of me trying to find out what she wanted to do.
Suggestions on what I did wrong in the past? Just curious from your POV.
She is finding excitement with the OM (or at least was at one point), have you ever spoken to her about what they did together and what specific things she liked about him.
Let it be known that I know discussing this OM and stuff they did together is uncomfortable, I don't envy your position just look at the end goal: knowledge is power and currently you're searching for answers.