Why am I angry that my married coworker might be having a baby when I’m married too?

I feel ridiculous even writing this, so I’m hoping strangers on Reddit can help me understand what is going on in my head.

I’m married, and I have a male coworker who I’ll call A. He is also married.

Over time, I developed some sort of attraction/fixation on him. There have been little interactions between us that I’ve probably analyzed way more than I should — eye contact, feeling like he was checking me out, just a general sense of tension. I genuinely don’t know whether any of it was mutual or whether I was simply noticing things because I was attracted to him.

Nothing has happened between us. In fact, once I realized how much mental space this was taking up, I basically started avoiding him like the plague. I know we’re both married, I know this isn't something I should feed, and I've been actively trying to shut it down.

The strange part is that somewhere along the way I started experiencing what I can only describe as unwarranted anger toward him. He hasn’t actually done anything to me. Sometimes I almost feel irritated by his existence, and I think part of that is my way of trying to kill whatever attraction I had.

Then today I found out that I’m pretty sure he and his wife are having a baby.

And it hit me WAY harder than it had any right to.

My immediate reaction was anger/upset, which makes absolutely no logical sense. He’s married. I’m married. Obviously he has a life with his wife, and having a baby with her is a completely normal progression of that life. I have no claim to this man whatsoever and I know that.

So why did this bother me so much?

I’m wondering if I had some imaginary version of him/us living in the back of my mind, even though consciously I knew nothing was ever going to happen. Maybe hearing about a baby made his marriage feel more "real" or permanently closed off whatever stupid fantasy my brain had created.

Has anyone experienced something like this? Where you know logically that you don't want or can't have someone, but finding out they're moving forward in their life still feels weirdly like a rejection or a loss?

I’m genuinely trying to understand my reaction so I can get over this and move on, not justify it.