It wasn't like Katherine could have what she wanted. She wanted Stefan, who didn't want her and she wanted a baby. If Peterson could make Stefan fertile, it was possible that he could make Katherine fertile as well, but it wasn't like she had anyone in her life to have a baby with. The old Katherine might have used someone for that purpose--provided that she actually had the means to have a baby--but she really had changed, even if they didn't believe it.
"My plan," she told him coolly, "is to go home and try to get rid of this headache before work." It was true that she had a headache coming on, probably not helped any by the alcohol she had consumed lately, but definitely the result of this confrontation now. She took the new bottle of shampoo from him as he shoved it toward her, careful not to drop the conditioner or the drinks she had in her arms at the same time. Without another word, she moved past him again.