At 7 months he is an adolescent, not normal yet but on his way. Normal chicken mating behavior between consenting adults:
The rooster dances for a specific hen. He lowers one wing and sort of circles her a bit.
The hen squats. This gets her body on the ground so the rooster’s weight goes into the ground through her body, not just her legs. That way it doesn’t matter that he is bigger and heavier than her.
The rooster hops on and grabs the back of her head. This head grab helps get him lined up to hit the target and helps him keep his balance, but it is also her signal to raise her tail out of the way so he can hit the target. Eggs don’t get fertilized if the tail is not raised out of his way so the head grab is very important.
The rooster touches vents and hops off. His part is done.
The hen stands up, fluffs up, and shakes. This fluffy shake gets the sperm into a special container inside the hen. Now her part is done.
Some hens will squat for practically anything in spurs, but most, especially more mature hens, expect him to have behavior suitable for a potential mate. He should dance for her, find her food, keep a lookout for danger, keep peace in his flock, and just overall WOW! her with his magnificence and self-confidence. Immature cockerels are seldom able to do much of that, certainly not enough to convince discriminating hens to willingly submit. That behavior normally comes with maturity, though maturity is not a calendar thing. I’ve had 5 month old cockerels that could manage a flock but I’ve also had some a year old that were just getting it.
There is something else going onto besides pure sex. The mating ritual is a dominance thing. The one on bottom is accepting the dominance of the one on top, whether willingly or by force. That cockerels hormones are driving him crazy about now with a desire to be flock master, the king of all he surveys. Many of the pullets probably have not had all their hormones kick in yet. Cockerels normally mature faster than the pullets and the pullets have a part or play in this too. They often don’t know what is going on, just that this former playmate is trying to dominate them and brother, that ain’t happening. Since he is bigger than them and a lot more determined, they normally run away instead of fight, though a more mature hen may not only fight but beat him up even if he is bigger.
He has to become flock master to do his job. How can he break up fights if they turn around and beat the stuffings out of him? What good does it do to warn of danger or tell them he has found food if no one listens to him? He is not thinking through all this. His hormones are just telling him to get out there and dominate. Nothing more complicated than that. Most of your females are going to resist his dominance until that teenager matures a little and starts behaving like he should.
From what you describe this is normal behavior for an immature cockerel, though this type of behavior often starts a month or two earlier. You may have one that is late-maturing.
It is not unusual for a hen to run away from a mature rooster in an all-adult flock, but usually that is just her testing him, to see if he is really interested. He may ignore her if she doesn’t accept his advances, but he might chase her too. If he chases, she may squat after just a few steps or she may continue to run. Nothing is wrong if he catches her and she squats to spread out his weight, even if serious chasing is involved. The more she resists thought the more likely she is to be hurt. She has to accept her part too, not just the rooster.
Good luck! Things could get pretty messy in there for a months until he matures enough to establish his dominance and get it accepted by all.