Girlfriend said she was falling in love with me and I had poor response

Little context: We (M 38/F34)had been dating for almost 3 months now. There were never any issues and everything was easy and flowing really well. We even commented it seemed like we had been dating longer than we had and had talks about future.

We were watching a movie when she told me "I think I am falling in love with you". I was surprised by this statement. I instantly responded back without thinking "I have really strong feelings for you too". There was an initial small reaction to that but we embraced and everything seemed fine at first. And to be honest, I thought I was responding with a similar statement.

Over the next week, she told me where she wanted to go for her birthday in March and I met her nephew for the first time. However, I started to notice she was contacting me a little less. We were talking everyday and exchanging messages. But from her end it was slowing down and I was always the one calling. She then canceled our date night and said she was just too tired and wanted to reschedule. This was not super surprising because she was working a ton of hours of late and got scheduled for more. She has been working a ton of hours in general.

However, the next day she text messaged me: I am just too busy for a relationship right now and you deserve someone who can spend more time with you, go on trips together. I dont want to bring you into my mess more because you will end up miserable because I just dont have time and not right for a relationship
Even with the change in behavior, this was surprising because how well things had been going in our relationship.

I tried to text her back asking for more info. She responded a day later saying she is sorry I am a great person but its just not right timing and she wants to end it now before its miserable. She agreed to do a call with me but then never answered her phone. I messaged her back I am happy to accommodate my schedule and sent her flowers. I never heard back.

I sent flowers one more time and she responded to me. We talked on the phone for 4 days straight with each conversation getting a little longer each time (but about basic life things) and then I asked her if she would be open to talking over coffee. She agreed. When that day came I texted to confirm but heard nothing and she never showed up. I messaged her that I was confused and she replied back sorry i was sick the other day and today I just have been super busy running around.

At this point, I feel the relationship is over. However, I keep wondering if I blew this with my response. It was just very fast end to something that seemed really promising.

TLDR: Girlfriend said she loved me, I was little taken back and didnt respond best way, she breaks up with me soon after