What Does It Mean When A Man Says He did not Feel A Spark? How Do you Build Chemistry?

Anonymous
On April 15th, I met this man via hinge; he is 33, and I'm 25; we began chatting every day.
On April 18th, he asked me out, so we had coffee for about 30 minutes, and then he asked me to have dinner with him, to which I agreed. We also visited a thrift store, so overall, the date was almost 5 hours long, but we had a good time, lots of laughter and banter and good communication.

I told him I had a good time and suggested we hang out again via the hinge messaging system when I got home on April 24.

So on Wednesday, April 27 he suggested we hang out again on Saturday, so he asked me what I would like to do, and I told him a picnic. Hence, we planned everything out and met up. He seemed to change his mind as the weather was dull, so he suggested we visit a board game cafe which we ended up doing. We played a conversation starter game called convo and chill and took turns asking each other questions about our views on life and relationships.
He eventually told me that he was exhausted as he is currently completing his Ph. D., so we walked back to the train station and hugged goodbye; our date yesterday was 3.5 hours long.

Anyhow, I did not hear from him until this unusual morning, but then he messaged me the following:

"Hey, Sorry for this late reply because I took some time to consider. Yesterday was a good time, and you were beautiful, but I am so sorry to say that I didn't feel a spark between us."
As you are passionate, open-minded and kind, there will be a good person for you, and you will find him.
Thanks for having time with me during the dates.

I wish you luck.

I then messaged him that there were no worries and Thanked him for his honesty and that he should take care.

I'm bummed because we only met 16 days ago, so for him to come to that conclusion quickly, I was surprised, but then I'm so grateful for honesty but would love to know how to build that spark that individuals often talk about? How do I make myself attractive?

Thanks for any advice given!
What Does It Mean When A Man Says He did not Feel A Spark? How Do you Build Chemistry?
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