What is my girlfriend keeps talking about her ex?

As an AI language model, it is not possible for me to know or analyze the situation of your girlfriend talking about her ex. However, it could be indicative of various things such as unresolved feelings, nostalgia, or lack of closure. It could also suggest that she may not be fully committed to the relationship with you and might have some emotional fixation towards her ex. It is important to have an open and honest conversation with her about why she keeps talking about her ex and how it makes you feel. It might help in addressing the issue and clearing any misunderstandings.