She might feel a sense of comfort. Since Carlisle is an authoritative and kind figure, his gesture could make Bella feel safe.
Bella could be initially surprised. Carlisle is not as close to her as Edward in a romantic sense, but his action shows a different kind of care. So she might be a bit taken aback at first, but then feel grateful for his concern.
He might be very empathetic. He could offer her a safe space and listen intently. Maybe he'll use his calm and understanding nature to make Bella feel supported.
Carlisle would probably be very calm and composed. He might give Bella a reassuring smile and say something like 'It's all right, Bella.' Esme, on the other hand, might look a bit flustered at first but then quickly regain her composure and act as if nothing out of the ordinary had happened.
Often, it starts with an unexpected encounter or a moment of realization. Maybe Carlisle sees Bella in a new light, not just as Edward's girlfriend but as an individual with her own charm. Then, there are small gestures of kindness and understanding between them that gradually build up the relationship.
In some fanfictions, their relationship might start with Carlisle being drawn to Bella's unique spirit. He, as an older and more experienced vampire, is intrigued by her resilience. Maybe he first notices her when she enters the Cullen family's orbit, and from there, a slow - burning attraction begins to form as they interact more and get to know each other on a deeper level.
Some fans would be outraged. Carlisle and Esme are a beloved couple in the Twilight series, and the idea of Carlisle cheating goes against the image many fans have of his character. They might see it as a desecration of the original story's relationships.
Maybe Carlisle wipes Bella's tears because he sees her as a vulnerable human in a dangerous supernatural world. He has a kind heart and wants to comfort her.
He becomes more vulnerable. Usually, Carlisle is seen as this strong, composed leader. But when he falls in love with Bella, his emotions start to get the better of him at times. He might second - guess his decisions more often.
In the fanfiction, Bella could initially be in a state of panic. She might try to run away from Edward, thinking he has just doomed her. However, as the shock wears off, she might become curious. She may start to notice changes in herself, like enhanced senses, and this could lead to her having a more complex reaction where she is both scared and intrigued by what Edward has done.
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.
Bella may react by trying to understand Edward's reasons. She could be more rational in some fanfictions and instead of just being sad or angry, she starts to investigate. Maybe she discovers that there are forces at work that she can fight against to get Edward back. Or she could decide that she doesn't need him and focus on her own growth and development, becoming a stronger and more independent person without him.