It is a rare gift to be able to be with a child and feel no 'age-gap' and no need for 'condescension'. As a young man I too had that gift. These were magical times and the response of the children told me it was only good. When I meet people again who were children then, their warmth and continuing friendship even after thirty plus years only confirms that.
Adulthood does call in the end. I lost my gift when I became a teacher. Not suddenly; gradually . . . though it did come back for a brief spell in my early thirties. The greatest danger for me was to think that losing my gift was somehow the end of everything . . . it took me many years to be able to admit that I no longer had this gift and allow others to take my place. I know you do not believe in God but perhaps you are seeing God anyway in your child friends?