Emma,
It is possible that you haven’t met that “special person” yet. You will sense it when you do. You don’t want to be with someone when you feel that you constantly have to be working to make that relationship successful. That should come naturally when you both genuinely care for one another.
As for the guy you met online– people can be anything they want with online communication. I sense a possibility that he has a family that he returned to. He may have been lonely while he was away and started the online communication. He really didn’t know you– so you should not feel that you are in any way to blame because he stopped talking to you.
So rather than make yourself unhappy in a relationship that obviously isn’t working, you might want to try going it alone for awhile? That is when you are most likely to meet someone you could really be happy with.
Best wishes,
🙂