Can ex lovers be friends?

If someone ask me that question, my answer is "it depends". It depends on how your relationship ends. In my own experience, relationship that ends without formal breakup is one of the big problem I experienced. It's hard for me to ask what happened to us, do you still love me, something like that. It's funny to remember that sometimes in your life, you loved each other like no one people around you. And then suddenly, without proper breakup, it's just like he or she is not existing.