The Twilight Saga starts when 17-year-old Bella Swan moves to Forks, Washington to live with her father Charlie after being raised by her mother Renee. Most of the series actually focuses on what happens to Bella after she moves to Forks and meets Edward Cullen and his vampire family, but there are several details included about what her life was like before that happened. And unfortunately, these details paint a sad picture of Bella's life before it took a turn for the supernatural.
Renee and Charlie were young when they first got married, and their relationship fell apart not long after Bella was born. Bella used to visit Charlie in Forks for the summers, but that didn't last long, so their relationship was relegated to Charlie visiting her for the holidays. This led to Bella not growing particularly close to her father and not knowing him all that well. However, she makes several observations after moving in with him about how similar they are to each other and how easy she finds it to live with him.
Bella says she is close to her mom, but she never can tell her the truth, mostly because Renee depends on her far too much. Bella knows the exact words Renee used when she broke up with Charlie and walked out on him, taking his only daughter with her. Bella was just a child, and it was unfair of Renee to put that emotional baggage onto her child.
The ease of Bella's life with Charlie is in direct contrast to what Bella as the narrator leads the reader to believe about life with her mom. Bella laments often that she has had trouble making friends with people her own age, and she remarks that she feels older than she is. She never directly draws the connection to the way her mother raised her, but the clues are in the details. It's reasonable to deduce that Bella feels like that as a direct result of her mother's immaturity and selfishness. She talks about being a young child and being responsible for the family finances while Renee would jump between expensive hobbies. And to make matters worse, Bella talks about how she had trouble affording to buy a wardrobe suitable for the weather in Forks, while her mother continues her frivolous spending.
Bella is also the primary cook when she moves in with Charlie because she had to take the role of caregiver in her relationship with Renee, and she extends that habit to Charlie. Charlie lived by himself for 17 years and took care of his own cooking and housework before Bella showed up, but Bella feels this need to care for her parent because it's the only way she's ever known.
When Charlie does care for Bella and look after her, she's surprised and often overcome with emotion as a result. When the weather turns icy, Bella spends all night anxious about her ability to drive her truck on the roads, though she never mentions that to Charlie. But when she wakes up one morning, she discovers that Charlie put chains on her tires without being asked. He simply did his job as a parent and looked out for his daughter and her safety. Bella gets incredibly emotional at the gesture and is deeply moved by his actions. Clearly, she is unaccustomed to being looked after and cared for, having spent most of her life doing things like that for herself.
Renee's selfishness becomes even more glaringly obvious in Midnight Sun when the reader is granted access to her inner thoughts through Edward. When Bella is in the hospital after her near-fatal attack, Renee is more worried about missing a phone call from her husband than she is about her daughter, who is lucky to be alive. Her thoughts are so loud and self-centered it is impossible to ignore how difficult Bella's life must have been growing up.
Bella explains to Edward that the reason she moved to Forks had nothing to do with her wishes. She admits that she felt she was a burden to her mother, and she moved in with her Dad to relieve Renee of the responsibility of raising her daughter. In reality, Renee would rather travel the country following her new husband as he played minor league baseball than be with her own daughter, and Bella knew how her mother felt.
Bella Swan's time in Forks was dramatic and full of life and death stakes, yet her life before was pretty lonely. Renee may be friendly and enthusiastic, but she was also selfish as a mother, which resulted in her child seeking love elsewhere.