you never loved them and they never loved you
you never KNEW eachother, at ALL

you were both in love with imaginary idealized versions that existed only in your minds, and as you learned and grew to know eachother and realized that ideal is utterly impossible you were forced to wake up and the love very quickly faded

"but I really did love him for him!"
I highly doubt it.
he was a means to an end
and so are you

use, and be used
:)