She may be running away to protect the baby. Maybe she fears that someone or something in her current environment poses a threat to the unborn child. It could also be that she wants to start anew, away from all the complications and expectations in her present life, so she decides to run away with the hope of building a better future for herself and her baby.
It could be her best friend. In many stories, best friends have a special bond and can sense when something is wrong. So, her best friend might start looking for her and be the first to find her.
Another reason could be that she wants to explore the world on her own terms. In the fanfiction, Mirabel may be tired of always being in the family's protective bubble. She desires to see what lies beyond the village and the mountains, so she runs away to start her own adventure.
She could also be running away to protect the baby. There might be some sort of danger or negative influence in her current place. For example, if there are people who would harm the baby or if the society she lives in is very judgmental towards unwed mothers.
There are several possible reasons. Firstly, a sense of being controlled. If Edward is constantly making decisions for her or restricting her actions, Bella would want to break free. Secondly, self - preservation. If she realizes that the relationship is putting her in more danger than she can handle, she'll run. Thirdly, a change in her feelings. Maybe she falls out of love with Edward or realizes she was never truly in love, but rather in some sort of infatuation. So, she runs away to sort out her emotions and her life.
One possible reason could be fear. Minato is a very powerful shinobi, and Naruto might be scared of him for some reason. Maybe he has heard stories about Minato that made him afraid.
One possible reason could be fear. Rin might be afraid of his own powers and the potential harm they could cause to Yukio. Since he cares about Yukio, he may choose to run away to protect him.
Perhaps he is running away from danger in Konoha. There could be a threat that he believes he can't face directly in the village, and he thinks Whirlpool might offer some sort of sanctuary or a way to become stronger in relative safety.
Maybe he's running away from some kind of danger or threat in his home village. There could be a group or an individual after him, and he believes that Kumo would be a safer place. It could also be related to some political unrest in Konoha that makes him feel like he has to leave, and Kumo seems like a viable option.
Maybe Harry feels a sense of guilt. In the context of the war, he might think that he's failed in some way by getting into this unexpected situation. He could believe that his new condition might put others at risk or that he's no longer the hero everyone expects him to be. So, to protect others or to avoid the shame, he decides to run away.
One possible reason is she's had an argument with her friends and feels she needs to get away to cool off.