One possible reason could be that he's worried about Ginny's safety during the pregnancy. He might be overprotective and his concern comes out as anger.
It could be due to jealousy. Perhaps Ginny has been spending a lot of time with another character, and Harry misinterprets their relationship, leading to his anger. In fanfiction, the writers often play with such emotions to create drama.
In some fanfictions, Ginny might be mad at Harry because of a misunderstanding. For example, she could misinterpret his actions towards another girl as being unfaithful. Maybe he spends a lot of time with Hermione on a project and Ginny thinks there's something more between them.
One possible fanfiction could be where they are excited yet nervous about the pregnancy. Ginny might be worried about how her Quidditch career will be affected while Harry is concerned about protecting his family from any potential dark threats. They could start preparing a nursery at Grimmauld Place with help from Hermione and Ron, painting the walls with magical murals.
Also, members of the Weasley family like Molly and Arthur Weasley are likely to be key characters. Molly would be all excited and involved in the pregnancy, giving Ginny all sorts of motherly advice and care. Arthur might be interested in how magic could be involved in the development of the baby, as he is always fascinated by the wizarding world's wonders.
In some fanfictions, their pregnancy could lead to a re - evaluation of their relationships with their friends. For example, Hermione and Ron might offer different kinds of support. Hermione could be full of practical advice on parenting and magical prenatal care, while Ron might be more of a comical relief, but still a great source of support. The story could also explore how the wizarding community as a whole reacts to the news of the Chosen One having a child on the way.
In many Harry Potter fanfictions where Ginny is pregnant, it often explores how Harry and Ginny handle this new phase of their lives. It could show Harry being overprotective, like making sure their home is safe from any potential dark magic threats. Ginny, on the other hand, might be depicted as being excited yet also a bit worried about how motherhood will change her role as a witch. For example, she might wonder if she can still be an active part of the wizarding community while taking care of a baby.
They might face security challenges. With Harry being a well - known figure, there could be dark wizards who might try to target Ginny or the unborn child. Another challenge could be the stress on their relationship. The pregnancy hormones and the added pressure of their responsibilities could cause some friction between them.
Well, a common storyline could be about the reactions of their friends and family. Hermione might be super helpful, researching all about wizarding pregnancies and giving Ginny advice. Ron could be a bit clumsy at first but then become really protective. And the Weasley family as a whole would be overjoyed, with Molly Weasley knitting tiny sweaters and baby blankets for the new Potter addition.