This sounds like you are missing the point. Flat out, how much time do you spend with the co-worker?

Time that we are in the same or adjancent rooms? Monday to Friday, 10am to 2pm. Time we are in the same or adjancent rooms alone? Zero.

Is your job closely involved with her job?

I'm struggling to answer this question because being involved with my coworkers' job is kind of my job. All of them, not just this one. I'm the database administrator and programmer who keeps the database and intranet app running smoothly and all my coworkers come to me when they have issues looking someone up, when they have trouble with the app, when they are trying to get data out of the database that they can't using the generic queries in the app, or if they have a request for a new feature.

Do you attend work parties/gatherings with her there? Etc...

No, I generally skip gatherings outside work because crowds are not my thing. The last time we (everybody in the office) had an out-of-office lunch was in December of 2017.

Yeah, both of these responses make me think you are not reading the room well.

That is entirely possible. I am quite literal and don't do subtext well. My wife is fully aware of this and knows that I give straight answers to straight questions. We've been together for years and while there have been some misunderstandings every so often, they are usually resolved whe she realizes that I just need more clarity on the situation.

The race with the co-worker was the breaking point, not the starting point.

That's an interesting insight that I hadn't considered and gives me a lot of food for thought.

From all of your responses here, it sounds like you do not have very good communication with your wife, and that you aren't on the same page.

This goes back to the previous response: we generally have great communication, because she knows that the best way to communicate with me is to go for it straight and that I'll always do the same. The communication breakdown over this is not the norm.