Will my ex miss me if I no longer contact him?

Whether he misses you or not is irrelevant.He has already told you that he only wants a platonic relationship with you and feels happier without you. You are the one who needs to decide whether you can accept him on his terms and be happy with that decision. Since it is clear and apparent that you still love him and want to continue to date him, that makes it your issue. Hopefully you have learned something from this experience and regardless of the reasons why you acted as you did in this relationship that caused it to go the way it did would change how you act in your next one.