Really? I thought that roosterless flocks of older chickens sometimes have trouble accepting a roo, and older chickens may reject a roo they don't think is up to snuff - she is the one chicken who has always been on top. Also, this guy doesn't seem to be a huge "wow" to the girls - most of the time his dancing does not get results. But they like to hang out with him, and yes, she is the only one rejecting him - after a couple weeks when they got along just fine. Something happened that I didn't observe that changed the relationship.
Yesterday went so-so - she continues to squat once for him, and run away the rest of the time. But she was able to hang out with the group, he allowed that, and she hung out sometimes close to him, so that was a good sign. On the other hand, he got feisty around food time - I think he gets riled up about the dynamic, and ends up taking it out on the other girls - he gets slightly agitated and makes quick moves, occasionally chasing away a girl, rather than playing the the big food provider roll. I made a point of only feeding with the two of them separated by the kennel walls, to try to avoid more direct confrontation. Possibly he may be one of those roos who is not as nice to the hens as he could be - or he might relax and act more normal if this conflict gets resolved.