Why are you always like this?

Why did you 'do that' (or a specific action)?

What prompts you to act like that/this?

Why do you continue to act like this?

What makes you think this behavior works for me?

What motivates you to behave this way?

I don't understand why you act the way you do. Can you please enlighten me?

Please tell me why you seem to never change?

I feel angry when you do that.

I feel like this behavior causes a problem.  Can we talk about it?

You behaved this way in the past, and I have to admit it still annoys me.

It seems like you automatically react by doing this.  Can you tell me about it?

You always act like a bitch!  I hate you! (Okay, that one didn't feel very productive, but I did translate it into e-prime  .)