People think a soul mate is your perfect fit, and that's what everyone wants -- well, what they believe they want. If you deserve hell, god might grant that prayer.
But a true soul mate is a mirror, an embodied reflection, the person who shows you everything you resist and that you allow to hold you chained; the person who brings these things to your attention so you can change your life.
A true soul mate is the most important person you'll ever meet -- they are storm, with lightning in their eyes. They tear down your walls and smack you awake. But to live with a soul mate forever? "Fuck that" isn't a strong enough term. Too painful.
Soul mates, come into your life to tear another layer of shadow off your eyes, and then leave. A soul mates purpose is to shake you up, cleave your ego; demonstrate obstacles and addictions, break your heart open so new light can get in, make you so desperate and out of control that you have to transform your life... they're the violent urge of awakening.