Well done CL I hope you are steadfast and resolute in this.
Again from a female POV all the things you listed, patience,loyalty,tolerance ect say to me, he really doesn't care that much about me, I am not worth fighting for,as long as his life doesn't change and I remain in the house.
Don't get me wrong, patience,loyalty and tolerance are admirable qualities. Resentment and passive--not so good.

This may be just me and not all women but if as your wife I was behaving as she does I would be wanting to see some anger some jealousy some sign that I belonged to you,that you wanted me and in no way shape or form would you put up with sharing.

To me she is screaming out for you to show some passion and I don't just mean in the bedroom.
She feels neglected,uncared for and unloved. Granted she could say all this verbally but maybe she feels driven to express that in other ways because for years she has been or thinks she has been telling you this.

She is 50, maybe her looks are going, she feels insecure as a woman and needs her confidence boosting,she wonders if "this" is all there is and so she is fighting the advancing years and her fears by proving to her self that others find her attractive and desirable and she can still "pull".

I am trying to put myself in her shoes,I know I am always critical of her behaviour but she has been the one to live with you and your passiveness all these years.
So just a few thoughts to add to your list of ponderings. You may disregard all but maybe I am right on one or two points.
Guess it all boils down to how much do you love and want her.
Blessings.