Airports hold some of the most honest goodbyes there are. Nobody’s acting cool at the security line.

Certain places remove the option of being cool about things. At a security line there is a fixed amount of time, no way to extend it, and somebody about to be gone for months, so people say what they actually mean. The honesty is not caused by the airport. It is caused by the deadline.

You do not need a departure for that effect. Say the thing you would say at the gate to somebody this week, while they are standing in front of you and nothing is forcing it.