Salade Niçoise

I am fighting with my Canadian girlfriend.
They are so polite and sensitive, it's almost impossible to have a proper spat.
Here's a typical example of a recent exchange:

Her: Kindly send me no further unpleasant e-mail and I will return the favour.
Me: Fine. Do what you like.
Her: Thanks for the permission.
Me: Thanks for the haughtiness.
Her: Indeed. And thank you for failing to listen to me.
Me: It's been my pleasure. And thank you for behaving like a madwoman, run amok.
Her: Hardly. And please do me the favour of honouring my wishes not to argue.
Me: Too many u's four me to take seriously, daurling.
Her: You...you...Imperialist!
Me: You Canadian!
Her: Hrumph!
Me: Right back atcha!
*click*