Dealing with rejection

I (25F) went on a date with a guy I met on a dating app (23M). The date was really nice and wholesome. We did a bunch of different activities, and I ended up going home the next day.

One thing that stood out was how expressive he was. He constantly told me that he was having a good time, enjoying my company, and that he thought I was beautiful. Before I left the next day, we went out for breakfast, and he said he wanted to see me again. So, we planned a date for two days later.

I went home feeling excited and reassured. The next day, I got a message from him canceling because he said that we didn't click in a meaningful way. I was very shocked and confused because the entire time we were together, he kept expressing how great a time we were having. He was the one who initiated the second date in the first place.

I guess I just feel kind of blindsided because I didn't see this coming, and it makes me feel like he was just pretending the whole time. We also slept together. I guess I just don't know how to navigate this situation. I asked him for clarity on what changed between then and now, and he has been ignoring me and has been very cold ever since he said he wasn't interested in me anymore.

I just find it so strange how people can be so unkind when they no longer want you. I'm having a hard time reconciling the sweet guy I went on a date with and this guy now. I know people are allowed to change their minds, but I just don't understand how you go from being really expressive and into someone to just waking up the next day and saying there wasn't a meaningful connection. I guess I’m just disappointed. Rejection is never nice but this one really stings.