Why does Offred want to have a fight with Luke?

Offred realizes that the relationship she had with Luke really isn't that different than the one she has with the Commander; she was in fact only mistress to them both. She perceived her relationship with Luke to be based on love, but has since realized that Luke never really seemed affected by the changes that were taking place and didn't seem at all concerned. She thinks in retrospect that maybe he was in fact happy with the changes. She was dependent on him, and her feelings didn't really matter........... in turn, she'd like to have herself a good fight.