Hi I am really not sure if I should post this or not but her goes.

I am confused I have read what you are saying and what I am seeing is that you have a decent relationship.
You and your wife can communicate. From what I am reading you both show interest in each other you talk and listen to each other about the course of your day which alot of people do not take the time to do and it sounds like you speak about your relationship on a regular basis. And I am sure there are other things not mentioned be it hobbies family or children. You spend time together daily in your conversations eatting together traveling together. That again is great.It does not sound like you spend large amounts of time fighting. But that you have found a pattern and yes patterns need to be changed up some at times to stop them from becoming boring but you sound to have a healthy pattern for the most part in my opinion.
And most of it sounds like it is together not apart. You are not watching TV in one room while she is watching it in another so there is a closeness and a contentment in your relationship alot of people lack. What is wrong with being content it brings along a feeling of safeness, security and selfworth. And is that not what most people crave most in life.

To me you have what most people want most. And you are thinking of throwing it away because she does not what start sex. It does not sound like she is adverse to having it she just does not pull down her pants and say lets do it.She even sounds like she is willing to say hey this is my fault you are not happy let me try to fix it. But you do not like her idea of how. Maybe the reason you are not satisfied is you have been fixing something that was broken for so long that you have not realized that is fixed just a hairline crack or two remain.
I am sorry but you stated your wife is 51 not sure how old you are. But maybe you need to look around at the population of lonely people out there.That are fighting disease and old age and dying with no one to talk to and tell how much it hurts to have no one that cares or worries about them going pretty much unnoticed through there life and think is that what you want does having sex 2 times a week verses 2 times a month mean so much that you would trade places with those people.I doubt they have sex 2 times a year or have anyone to talk to about there day.

You can meet someone and have one orgasim after another every day. But you still may not have what it sounds like you have now A partner in life through thick and thin.

My suggestion work on being satisfied.