Running away from it all

Why is it that every time something good happens I feel the need to run away from it?
There its no rhyme or reason to my madness or methods as to why I think this is too good to be true.
My significant other is a good man. He is there for me, supportive of all my goals and dreams. I don't understand why i want to run away and hide.
I'm afraid I've begun to see myself as crazy. I'm not trying to push him away... I just no longer know where the boundaries are.
Sometimes I look in the mirror and I don't recognize the person staring back at me.
I'm scared of my reflection. I'm scared of who I might see.