A one year old rooster this time of the year in Massachusetts? Is it possible he is actually closer to 8 or 9 months old? That would be a cockerel, not a rooster.
Different cockerels mature at different ages. I've had some, a very few, pretty much mature and accepted by all the hens as flock master at 6 months. I had one that did not achieve acceptance from the last of the mature hens until he was 11 months. The personality of the individual hens, especially the dominant hen, has a lot to do with that too.
When you don't have a dominant male in the flock a hen will often assume those duties and take control. When a cockerel matures enough to try to take control she resists him. He is bigger than her but she just won't submit and accept his authority. I've seen this before. Sometimes there may be some actual fighting but usually she runs away and he chases. For about two days he would go out of his way to attack her like you describe, though I never saw blood. After two pretty rough days of this she finally submitted and accepted him as boss. They became best buddies.
I don't know enough about your flock to know if this is what is going on or if it is something totally different. As you said the comb is mangled I'd assume it is bloody. Instead of isolating the cockerel/rooster I'd isolate the hen from the entire flock for a week. Heal her comb and see if that separation changes her dynamics with the flock. Then put her back with the flock when you can observe. What I'd hope to see is that he mates with her to welcome her back to the flock and show that he is dominant. That may involve some chasing. But hopefully her dynamics with him and the entire flock will have changed enough that the constant attacks stop.
I've butchered males before because of their behaviors. I've also butchered hens because of their behaviors. I know it is popular on here to always blame the male (especially if he is an immature cockerel) but sometimes when I remove the hen the problem goes away. From what I've seen sometimes the problem is the female, not the male.
