A ex reaching out then going cold could be due to a variety of reasons.
• They may feel overwhelmed by emotions and need time to process them.
• It is possible they are unsure about how the communication will unfold, so they take a step back instead of continuing the conversation.
• It can also be a sign that one partner still has lingering feelings for their former significant other.
Regardless of why an ex might reach out then go cold, it is important for both parties to express their feelings in an open and honest manner if either wants to move forward with any kind of relationship.