Teen relationship

Hi, so recently I’ve been talking to a boy. Chris. He dates my best friend but after they broke up and me and my friend stopped being friends he started talking to me told me he liked me and i said i liked him but then a few days later we met up and he ditched me. Then he ghosted me. Then he started dating someone and was talking to me while they were dating broke up with his girl for me. Then started ghosting mr again. And he keeps finding ways to start conversations and after I catch feelings he ghosts me again.

What do I do. Please help