Why does this guy pop up in my head? I only dated him once, long ago?

I am sorry to analyze as such he already taken that why he did not reply to your message. Plus he was the one who interviewed you for a job and ate dinner at the same time. Well he may not meant to be yours but, you will find a nicer one in the future and keep looking harder. Do not give in for the wrong one and go no where in life.