strange serama behaviour

[S1ilkieGirl99]

HI, I have two serama chickens - a hen and a cock. They are so friendly and I adore them! The cock has been crowing for about 3 weeks now - at just four months old. he is fully developed - comb and all. he has started treading on the hen - she is half his size and clearly not enjoying the attention! he has also started pecking me and being very spiteful. I am concerned for the hens well- being. I cannot separate them due to space and they get stressed whenever separated. should I get another hen? should I separate them? is this normal behaviour - my silkie cocks have never been so mature and spiteful.
PLEASE RESPOND!
Thank you for reading!