It's challenging to provide a specific answer without more context about the situation, but there are a few possible reasons why someone might keep you around even if they still have feelings for their ex:
Uncertainty or ambivalence: The person may have mixed feelings about their ex and their current relationship with you. They could be torn between their lingering emotions for their ex and their feelings for you, leading to uncertainty about what they truly want.
Fear of being alone: Some individuals may keep someone around as a backup option or for companionship because they fear being single or don't want to be alone. They may not want to end the relationship with you until they are certain they can get back with their ex.
Comfort and familiarity: Being with you might provide a sense of comfort and familiarity, even if they still love their ex. Ending the relationship and moving on can be daunting, so they may prefer to stay in a situation they know, even if it's not fully satisfying.
Hoping for a reconciliation with the ex: They might believe that maintaining a relationship with you won't interfere with the possibility of getting back together with their ex if that opportunity arises.
Avoiding confrontation: Breaking up with someone can be difficult and emotionally charged. They might keep you around to avoid confronting the issue or causing pain to both of you.
Genuine care and affection: It's possible that they do have feelings for you and care about you but are still dealing with unresolved emotions from their past relationship.
Regardless of the reason, it's essential for you to prioritize your emotional well-being and consider what you want from the relationship. If you find yourself in this situation and feel uncomfortable or unhappy with the dynamics, it may be worth having an open and honest conversation with your partner about your feelings and concerns. In some cases, seeking the guidance of a therapist or counselor can help navigate the complexities of the situation and determine the best course of action for your happiness and emotional health. Remember that you deserve to be with someone who fully reciprocates your feelings and is committed to the relationship.