In some fanfictions, if Edward leaves Bella, she might become stronger and more independent. She could focus on her own life, perhaps pursue her studies or hobbies more intently. For example, she might finally decide to travel the world and discover new things on her own.
Well, it usually leads to a lot of drama and emotional turmoil for Bella. She's left alone to deal with the pregnancy and all the complications that come with it.
One possibility could be that Bella has to face the challenges of pregnancy alone. She might struggle with the physical and emotional changes while also dealing with the absence of Edward. The Cullen family could be in a dilemma about whether to support her or not, as Edward's departure might have left them with mixed feelings. And Bella could start to discover new powers or abilities within herself as she copes with the pregnancy, which could be a big part of the fanfiction plot.
One possible storyline could be that Edward leaves due to his fear of endangering Bella and the unborn child. He might think that his vampire nature could bring harm to them, so he decides to distance himself to keep them safe.
Edward would probably be very confused at first. He would try to understand why Bella would leave him for Rosalie. He might start to analyze all their past interactions, looking for signs that he missed. Eventually, he could become angry, not at Bella directly, but at the situation. He might also feel a sense of betrayal, not just from Bella but also from Rosalie in a way, since Rosalie is 'taking' Bella away from him.
Well, for one, the whole concept of their courtship would be different. Since Bella is now the vampire, she would be the one with the enhanced senses and abilities. She might be more forward in the relationship as she doesn't have the same insecurities as she did as a human. Edward, on the other hand, might be more hesitant and in awe of Bella's newfound power.
Bella may become a more adventurous character. Maybe she decides to try new things that she was always too afraid to do before because Edward was so overprotective. She could start going to parties, trying extreme sports, or exploring new hobbies. This new adventurous side of her would make her a more well - rounded character, and when Edward returns, he would see a completely different Bella.
One possible ending is that Edward realizes his mistake and comes back to Bella just in time for the birth of their child. They then form a family together and the Cullen family accepts them wholeheartedly. Another ending could be that Bella decides she can raise the child on her own and she cuts all ties with Edward. She becomes a strong, independent mother. Or perhaps the baby has some special power that reunites Edward and Bella in an unexpected way, like the baby's power being able to heal the rift between them and they all live happily ever after in the end.
She might be devastated. Bella was deeply in love with Edward, so his leaving would be a huge blow. She could cry for days and feel like her world has ended.
The Cullen family might also get involved in different ways. Some of them could be sympathetic towards Bella and offer their help, while others might be more hesitant due to the implications of a half - vampire baby. Esme, for example, might be very motherly and try to take care of Bella, while Rosalie could have mixed feelings because of her own history with not being able to have children.
Bella might become more independent. She could start to rely on her human friends and family more, like Charlie. She would have to face the challenges of pregnancy without Edward's support, which could make her stronger in the long run.