I was hoping this would only happen if his affection was low at that point of the game. I've already had him propose and everything. It's weird for him to try to kill someone who is practically his wife just because he "owes Baras his career."
I finally got to this point myself, after marrying the guy and him sending me letters about our relationship and so on. Yup, he does it - he betrays you regardless.
But if it makes you feel any better, our characters aren't like us and they don't live in a world like ours. It seems that marriages for sith are as much about gaining social status and power or moreso than they are about love. After all, the penalty for weakness in this world is often an early demise. So in a way, my character just kinda rolled with the inevitable and forgave him. These things happen, why let it spoil an otherwise good lay.. er, "marriage".
But then again, I am playing a light sw. Someone with a lot less patience and a much bigger god complex than me handles it differently.