You don't have hens and roosters, you have pullets and cockerels. They are still immature, they are going to behave differently than mature chickens. That could be part of your problem. The boys' hormones are probably acting up. The girls are going through puberty also. There may be some changes going on on their side of the pecking order too. Adolescence can be a rough time.
I think the size and layout of your coop might be a big factor here. When I've seen this behavior before it generally means they are getting beat up when they try to roost so they look for a safer place. My coop is pretty big with different places to sleep so it's usually within the coop but occasionally some try to stay outside. With mine it's the older hens causing the problems with younger birds so some differences with your situation.
How big is your coop and how is it arranged inside, especially the roosts. Can they get away from bullies on the roosts? Where can they sleep inside if they are not allowed on the roosts?
I think your problem probably is the boys. It's possible that one or both cockerels are waiting to mate with the pullets as they enter. Once they make it to the roosts (depending some on what your roots look like) they might be safe from the boys but they can't get that far so they avoid going in. If this is the problem removing one or both of the boys may be a solution. Removing doesn't have to mean killing, selling, or giving away. Housing them separately so they are not part of the equation can tell you if it is a possible solution. You will still probably have to keep putting those pullets in after dark for a few nights so they learn they can go inside.
I don't know for sure what is going on. Age/maturity may be a factor, size and layout of the coop may be a strong contributor. If your coop is big enough adding a separate roost might help. Removing one or both of the boys until they grow up may give you some insights as to the problem. Other than looking at those the only suggestion I can make is to consistently put them in the coop after dark in the hope they get the message.