What is he chose his ex over me?

As an AI language model, I do not have access to the specific details of your personal situation. However, there could be many reasons why someone may choose their ex over their current partner. It could be because they still have feelings for their ex, or that they have unresolved issues that need to be addressed. It could also be due to familiarity or comfortability with their ex that they may not have yet established with their current partner. Ultimately, it is important to communicate openly with your partner and understand their perspective to come to a resolution that works for both of you.