I would maybe try and avoid saying "I can't be bothered" because those are fighting words.

W: I have plans, maybe we can chat another time! <big crazy happy smile with a cheerful wave?

If you say "I can't be bothered" she could say "well, screw you a**s hole, I can't EVER be bothered by you either!"

If you say it like a crazy happy person she could say "well, okay, sounds good" because you have stated our intentions w/o any "conflict words"

CityGirl <--- has had waaaaaaaaaaaaaaaaaaaaaaaaay too much therapy