Yes, Chiyo is concerned that Ookuma may treat Nagatsuki badly, and, yes, she has shown disdain for him, and, yes, she is stupidly encouraging her friend to have a romantic relationship with someone she knows, at first hand, has a history of being a jerk. But none of this precludes lingering romantic feelings. Just think about all the women all over the world who are routinely abused (physically, emotionally, or both) by their significant others, but won't leave him because they are still madly in love with him.