What happens when you dont reply to your ex will depend on the nature of your relationship and why you are not responding. If your relationship was toxic or abusive, not responding may be a necessary step towards healing and moving on. On the other hand, if your relationship ended amicably, not responding may cause confusion or hurt feelings. Its important to remember that everyone reacts differently to being ignored and that you cant control your exs actions. If you need space and dont want to engage in communication, its essential to set clear boundaries and stick to them.