If I a relationship ends with a 'see you later' is it really over?

Me and him are sweet and easy. Maybe too easy. We have trouble being sure what the other really wants beyond the obvious smooches and cuddles and clever back-and-forth. We don't text, (for impossible reasons). So how can I know if he wants to get back together at the end of summer? I don't want to be the clingy one that didn't know it was just a fling for him when it meant everything to me. Should I write him, or let the memories keep me sane?