Hooked up with ex- wtf happened?

So my ex and I were long distance, and we broke up in June. We started talking again a few months later and we became best friends again. I saw him today after 10 months and something felt SO off. We're normally so comfortable with eachother but something didn't click. We went further than we had when we were dating- we made out a lot, I sucked his dick, he ate me out a little bit, and we tried to have sex but we couldn't get it in. We tried A LOT (different positions too) and we just couldn't. After that happened, we got dressed and he was like "let's pretend that didn't happen" (but he was joking). Afterward he kind of made an excuse of why I had to leave (we're both 17 btw) and I got picked up. I feel so weird emotionally because I've spent 10 months fixated on him and I'm surprised by how awful everything went. I honestly kind of want to cry, I don't know what to do. He would always tell me he loved me so much and I love him to bits.  Please help 😰😰😰