I wonder whether it would help or ease your mind at all, to think about your first love and ponder what was really good.
Not superficial stuff, like the fact that he looked cute in golf hats or made good French toast. (It's easy for people to make the honest mistake of thinking that they must have someone who looks or sounds like their lost love.)
But deeper stuff.
What parts of his energy really reached out to you, or elicited the best from you?
What wonderful lessons did you learn from him?
How did you grow when you were with him?
Did it open some part of your heart and make you more aware of everyone in your life?
Did he say something especially helpful or wise or endearing?
Was he compassionate about traits in you that make you feel insecure?
What was the difference in your life paths that eventually pulled you apart?
It could be that this longing is really a whole precious book of lessons about what you really need and what can make you happy.
Meditating on these things can help us be more aware of similar promising qualities in other new acquaintances. Maybe it could become easier to recognize a new soul mate when he comes along.