Well do you let him hang out with his friends? It’s weird that it was so random. I would try to give him space for a few days and then reach out and just ask him to help you understand. Then you can ask him why he never mentioned it and why he did it after the good day you had. Make sure you come off calmly and just as genuinely curious and wanting to know for your sake, not to try to manipulate him to getting back with you. Hopefully that will help you get some clarity on what to do next. Good luck!