First relationship lasted only 3 days

I’m 19M, and this was my first relationship ever. I’m trying to figure out where I went wrong, because honestly I still don’t really understand what happened.

I met this girl at university almost a year ago, but we barely talked until this summer. I asked her out after our finals and she said yes. We went for dinner and a movie, and I thought it went pretty well. She was leaving the next day to go back to her home country for a month, so we mostly just texted while she was away.

She usually took a few hours to reply, and looking back, there honestly wasn’t that much flirting from her side. I was probably more invested than she was, but I didn’t really notice it at the time.

We went out again after she came back. We got food, played some games and walked around. I paid for most things on our first two dates. She also gave me a small gift, which meant a lot to me because I really liked her.

Then I had to leave Tokyo for about two weeks. During that time I started getting more attached. I told her I kinda missed her, and she just went along with it. Later I said I was getting a little addicted and wanted to see her, and she said we should hang out again soon when I got back. I took that as a sign that she was probably getting more interested too.

When I came back, I confessed to her in a park. She said yes. We held hands for the first time, and later I asked if I could kiss her. She said yes. It was literally my first confession, first relationship, first kiss, everything.

The next day we went out again because she suddenly had free time. It was raining heavily, we held hands, I put my arm around her, and she told me she had already told her family about us.

But I think this is where I messed up.

Since it was my first relationship, I got excited and probably moved too fast physically. I kissed her several times, smelled her hair and told her it smelled nice, and kept asking about going to my place to play games. She eventually told me that smelling her hair made her uncomfortable, so I stopped immediately and apologized. She was okay with kissing, but later told me that the physical stuff in general had moved too quickly.

That night she sent me a long message saying she wanted to slow things down. I apologized and told her I understood.

Three days after we officially started dating, she broke up with me.

I called her because I was completely confused. She said it wasn’t because of one terrible thing I did. She said she did have feelings for me, and that accepting my confession wasn’t fake. She genuinely wanted to give the relationship a chance, but eventually realized she couldn’t be in a relationship.

I asked if there was any chance romantically in the future, and she said no, although we could still hang out as friends. I asked what advice she would give me for my next relationship, and she said I should spend more time getting to know the person properly.

So now I’m trying to understand what I actually misread.

Was I simply inexperienced and moving way too fast? Did I mistake her being comfortable with me for stronger romantic interest? Or can someone genuinely like you, agree to date you, and then realize a few days later that they don’t actually want a relationship?

I know I probably made mistakes here. I’m just trying to understand which part of this I should actually learn from, rather than assuming the whole thing was fake.