I can offer some general possibilities as to why your ex-girlfriend might still have your number:
Unintentional Oversight: It's possible that your ex-girlfriend simply forgot to delete or block your number from her contacts after the breakup. If she hasn't had a specific reason to remove it, she might have kept it out of habit.
Nostalgia or Emotional Attachment: Your ex-girlfriend might still have feelings for you or have a sense of nostalgia attached to the relationship. Keeping your number could provide her with a sense of emotional connection or comfort, even after the breakup.
Remaining Friends or Civil Relationship: Some people choose to maintain a friendship or civil relationship with their ex-partner after a breakup. In such cases, they might retain each other's contact information for occasional communication or in case they need to reach out for any reason.
Practical Reasons: There could be practical reasons for keeping your number, such as needing to coordinate shared responsibilities, returning personal belongings, or staying in touch for mutual friends or family.
Hoping for Reconciliation: It's possible that your ex-girlfriend is holding onto the hope of getting back together someday, and keeping your number is a way for her to stay connected in case circumstances change.
Difficulty Letting Go: For some individuals, deleting or blocking an ex's number can feel like a final step, and they may be struggling to let go completely.
Remember that everyone's situation is unique, and the reasons behind your ex-girlfriend still having your number could be entirely different from the possibilities mentioned above. If you have concerns or questions about this, the best course of action would be to communicate openly and honestly with your ex-girlfriend. Discussing your feelings and boundaries can help both of you gain clarity and move forward.