Let it be! You can always love him even after he married. The beautiful is for you to appreciate and admire. Sometimes, the moment you gain it, the moment you lose it. So, just to hold our love might be the happiest thing for us.
I think he understands your feelings, but he like girls of other types.
One way love is sad, but there is no good way to change it.
Hope you find the next man soon.
Maybe you can shift your focus from work a little and go out more. There are many lonely people in this world. You will find the one who's right for you.