I agree. Me and my fiance have a friendship-based relationship. He likes to pay for dinner if and when we go out, but I usually offer him the money for what I ate. He usually doesn't take it, but I leave it in his car or stick it in his poket anyways. Every so often I do let him pay if he really insists. It makes me feel guilty having him pay, but it makes him feel guilty if he takes my money, so either way one of us will feel guilty! Your best bet is to just pay for what you ate. If it was her idea to go out, I'm sure she'd have no trouble paying for her share.