The pain of Leaving

Picture this. A father is leaving on a long trip. He checks in at the airport. He let's his ticket be approved and he enters the area for only the passengers. He turns around. He sees his 3 year old daughter crying. He can't help it but the tears fall from his eyes. I've almost forgot the pain of someone close leaving. The expression that I saw on the father's face truly expressed that pain. I could feel it as though it was happening to me.