Went on first date (that went really well) and a few days later they're not ready to date

Want to know your assessment of my recent situation:

Background I was dating a medical student in her 3rd year. We met on a dating app.

We had a fairishly short first date (~2hours), which was really nice.

Conversations flowed, lots of asking question, getting to know each other, fun bandwidth, honestly probably my best date in a while even though we did nothing.

We continued on with the conversation over text the next 2 days (just more humor and remembering details about each other from the date, and then she ghosted me for 2 days and got back to me with the "I had a really nice time last weekend but I realized I am not in the headspace to date. Wishing you the best.

This turned my "I like this girl, and I'm curious to see where things go" feeling into a desperate "I must have this person" feeling and I'm waking up with pangs of anxiety and dread that this person closed the door on something neither of us got to see through.

I responded by chalking up like it's no big deal and that she can keep my number and be friends. she agreed and that was the end of that.

The thing that got me was that 2 day gap where she was otherwise very responsive but just didn't respond. what changed? I know one of those days she didn't have class because it was observation day but who knows. Maybe those two days she had another guy lined up? Maybe she took those two days to gather her feelings (talked with friends, etc) about what she wants and needs to prioritize at this point in her life. For context, She's in her late 20s. I can still see she's on the app in my matches and haven't deleted it so maybe she is still entertaining others? idk

I'm thinking any of the following options happened:

  1. She truly is busy and overwhelmed with medical school
  2. Something changed about her feelings about me
  3. She's involved with someone else like an ex, or someone new she likes better?
  4. Perhaps I moved too fast? I dunno.

I'm not used to rejection . So bizarre. I cannot stop thinking about her and what our future could have been.