Sorry to hear that.

Did he explain why he doesn’t “feel like himself” anymore? If it’s something to do with him, you need to figure out a way to accept this or it Wil drive you crazy. If it’s something like you rely on him too much emotionally [example] perhaps you should try some emotional mastery and take this alone time as an opportunity to grow as a person. While it’s nice to have someone to talk to and help work through emotions with, the other person can get drained. Idk if you call a helpline or seek a counselor but it might help you and take the pressure off him.

Another point you should do some personal care for yourself, not because he might come back. This situation is a blessing in disguise. It’s sad, and I know it won’t be easy, but one day you’ll look back and be grateful. Good luck to you.