I'm a chap, had the same experience years ago, went out with a fantastic girl, then she had to call time due to work issues and moving away, but we kept in touch, then got together again for a few wonderful months, for whatever reason, she again decided to call time - which she was entirely in her rights to do.
For about a year after I moped, thought of her a lot, hoped she might email or message, but of course she wasn't thinking about me (which again she doesn't have to) - your mind can hold onto hope, dreams, imaginations, but that's all they are and its a waste of time, because other opportunities are passing you by.
This guy, for whatever reason just doesn't find a spark with you, that's not your fault, or his fault, just life - let it go and there will be someone else.