It's understandable that you're feeling hurt and confused about why your best friend doesn't take pictures with you, despite her willingness to do so with other friends. There could be several reasons for this behavior, and it's important to consider the context of your friendship and her personality.
One possibility is that she feels more comfortable and relaxed around her newer friends, making it easier for her to take pictures with them. It's also possible that she has certain expectations or insecurities when it comes to taking pictures with you, leading her to avoid it. Alternatively, she might not realize the impact of her actions on you, or she could be going through personal issues that make her less responsive to social situations.
Regardless of the reason, it's essential to communicate your feelings with your friend openly and honestly. It's possible that she's not aware of the message she's sending by not taking pictures with you, and having a conversation about it could help clear up any misunderstandings. If you're unsure how to approach the topic, you could consider seeking advice from a mutual friend or a trusted third party who can provide an objective perspective. Ultimately, open communication and a willingness to understand each other's perspectives can help strengthen your friendship and prevent misunderstandings in the future.