help?

how do I tell a person that I lost feelings, even though I liked them first? like holy fuck they deserve SO MUCH better.

I wake up everyday with goodmorning texts, and go to sleep at night with goodnight messages. He randomly asks for my pictures and puts me in his stories. He doesn't hesitate to say my name whenever someone asks if he likes someone. Everyone knows how consistent, reliable, and how much of a green flag he is. He's such a sweet guy and I constantly self-sabotage EVERYTHING. The moment I knew it, I have already lost interest in us:< like I don't really like him as much as I used to before, you know? I don't feel the spark anymore.