Why would your soul mate cut off all contact after making promises to you?
Because they are not your soul mate. This is called "game",
which obviously you didn't recognize. How long did you know this
person before you slept with them? It sounds like HE got what he
wanted and is now gone. (i know you're a woman because only women
ask these questions). Your soulmate is someone you will trust...you
can depend on his word to either do or try to do the right thing by
you. It won't always happen because we're human and not perfect,
but you can still say that the person is dependable and cares about
you as a whole. This person cared about himself only and you just
didn't fit whatever criteria he was looking for at the time. So,
now you have to re-focus your attention on yourself and move on.
Don't do it thinking that he is going to recognize and come back to
you...do it because it makes you feel good and builds your own self
confidence and worth up. Next time you'll know better (maybe).