One possible reason could be fear. Maybe Hermione is afraid of how Draco will react. Given their history in the wizarding world, with their houses being rivals at Hogwarts and different beliefs, she might think he'll reject her or the baby. Another reason could be to protect the baby. There could be some threats or dangerous situations in the wizarding world that she believes Draco's knowledge of the pregnancy would put the baby at risk. For example, there could be dark forces that target the children of powerful witches and wizards, and she wants to keep the baby's existence a secret to safeguard it.
Hermione could be hiding her pregnancy from Snape because she's not sure of his feelings towards her. There may be an ambiguous relationship between them. She might be in love with him, but not sure if he feels the same. And she doesn't want to burden him or make things awkward between them. Or perhaps she suspects that Snape might be involved in something dangerous, and she doesn't want her unborn child to be dragged into it.
She could be using magic. For example, she might use a concealment charm on herself to hide any physical signs of pregnancy. Hermione is very skilled in magic, so she could easily cast spells that make her look the same as before. She might also avoid situations where she would be in close contact with Draco. By staying away from him as much as possible, she reduces the chances of him noticing any changes in her.
One possible reason could be a conflict of values. Hermione is a strong advocate for justice and equality among wizards and non - wizards alike. Draco, on the other hand, was brought up in a family with pure - blood supremacist views. Hermione might run away from Draco in a fanfiction if she realizes that his views are unchangeable and they are fundamentally opposed to her own. For example, if Draco makes a derogatory comment about Muggle - borns in front of her, it could be the last straw and she decides to run away.
Maybe Sakura is afraid of the reaction from her friends or family. So she decides to keep her pregnancy a secret at first. She might be worried about how people will judge her, especially if she's in a difficult situation like not being in a stable relationship.
Maybe she wants to avoid causing unnecessary worry among her friends and comrades. They are often involved in dangerous missions, and if they knew she was pregnant, they might get distracted. Naruto might think it's better to keep it a secret until she figures out how to handle the situation without disrupting their important work.
One possible reason could be the long - standing rivalry between Gryffindor and Slytherin. Hermione, being a Gryffindor, has always seen Draco as an adversary. So, in a fanfic situation where they are brought together in some way, her past experiences and prejudices might make her scared. For example, Draco has taunted her and her friends many times before.
Maybe it's because of their different outlooks on life in the wizarding world. Hermione is very much about following the rules and using magic for good and knowledge, while Draco has been more influenced by the power - hungry and sometimes underhanded ways of his family. This could lead to constant arguments and ultimately a break - up.
One possible reason could be their different backgrounds. Draco is from a pure - blood wizarding family with traditional values, while Hermione is a Muggle - born witch. Their families might not fully accept each other, leading to constant stress and ultimately divorce in the fanfiction. Another reason could be differences in their career goals. Maybe Draco wants to focus on maintaining his family's status in the wizarding world, while Hermione is more interested in promoting Muggle - wizard relations and her own academic pursuits, causing a rift between them.
Well, sometimes in these fanfictions, Draco hides his pregnancy because he's in a secret relationship. For example, if he's in love with someone from a different house or a different social standing. He might be afraid that if his pregnancy is discovered, the relationship will be exposed and there will be consequences. Also, there could be a plot where he discovers some magical mystery related to his pregnancy that makes him think he has to hide it, like there's a prophecy or some dark magic involved.
One possible reason could be that Draco has had a change of heart. Maybe he realizes that Hermione is a person worthy of protection regardless of her House or her friendship with Ron. He might have seen some injustice about to befall her from Ron and his Gryffindor bravado getting out of hand.