I've probably been that person at times. I lost springboard diving, and eventually my ability to walk for a long time in a slow and relentless process that for ages had doctors befuddled or just wrong. It was hell. And even now, though I've largely regained the ability to walk, it still hurts. It still hurts to have lost that way of expressing myself. And I suspect that's what's really missing for her as well.
I encourage you to approach her gently and tell her that you're concerned. That it's entirely normal to grieve something like this, but that she doesn't seem to be moving on, and that it might be worth talking to a professional for a little while to get some help with this.
I also support putting time limits on how long she can talk about it. Maybe it's just 5 minutes of a get together.
The other thing I'll point out that may not be clear, is that she may not have something else she is proud of to talk about. When I was in college, fresh off an injury, I didn't always have a lot going on. I had school, but my issues with my diff eq prof didn't tend to be interesting for long. I could tell you in detail about the plans for my next surgery, but it wasn't great dinner table conversation. I could tell you about how hellish it was trying to adjust to not walking, and later to using a wheelchair on an incredibly inaccessible campus. In short, for years, while I had positive moments to talk about, in all honesty just coping took a large part of my time and energy. And people didn't want to hear that stuff. It left me with very little to talk about sometimes (eta) which left me telling stories about my past to try and sound interesting, and less depressing.