Yes, it is entirely possible for a girl (or any person, regardless of gender) to live her whole life alone if that is her choice and preference. People have diverse lifestyles and circumstances, and many individuals choose to remain single and lead fulfilling lives without a romantic partner.
There are various reasons why someone might choose to live their life alone. Some people prioritize their personal goals, careers, or passions over romantic relationships. Others may have had negative experiences in the past that lead them to prefer being alone. Some people simply feel content and happy in their own company and do not feel the need for a romantic partner.
It's important to remember that everyone's life journey is unique, and there is no one-size-fits-all approach to happiness and fulfillment. The key is to respect and support individual choices, as long as they are not harmful to oneself or others. If someone chooses to live their life alone and they are content with their decision, there is no reason to view it as a negative or undesirable outcome.