Dropped by a guy overnight

So I’ve been talking to this guy from my school for a few weeks now. He used to initiate everything. We would Snapchat every day, and he’d always open my messages and reply to me at a reasonable time (usually within a minute to an hour). He would suggest cute date ideas, ask all sorts of thoughtful questions about me, and overall just gave off the impression that he liked me. I felt super special that for the first time in my life a guy wanted to chase after me and flirt with me. All my friends thought he liked me too. So anyways two Saturday’s ago he asked my to FaceTime him and we FaceTimed for hours. It was a great conversation- we both seemed to love each other company. However that seemed to be the very last good interaction I’d have with him. Since then he takes hours (sometimes almost a whole day) to respond to me, and his answers are so dry and so dull it’s like he dreads talking to me. We were best friends on snap and now we no longer have the heart. I know it sounds silly but it did actually hurt my feelings when I saw the heart emoji was gone. I see him flirt with other girls now, and a mutual friend of ours seemed to hint to me that he was no longer interested. I honestly just feel so stupid, and I’ve just been in such a slump. We still have a snap streak going, and I’m not sure if I want to try to keep talking to him, leave him on open, or leave him on delivered. Does anyone have any advice, or just a perspective on the situation? Thank you! I know that it’s not the biggest issue, but I am struggling with it, and it would be nice to hear from someone outside of my friend circle.