Why did a COWORKER GET PROMOTED THEN LEAVE THE JOB AND NOT contsct me since and Its been months?

Everyone used to say they thought we were a couple and look good together and assumed we were together and guys would try to make fun of my by saying i liked him. That was for like a year.
Why did a COWORKER GET PROMOTED THEN LEAVE THE JOB AND NOT contsct me since and Its been months?
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