Airports can be a pretty romantic setting for emotional hellos and goodbyes — see any one of a slew of rom-coms from the past 30 years for reference.
If you're reuniting with a special someone and the mood strikes to declare your love in the most permanent way imaginable, you can actually swing by a jeweler and pick up an engagement ring to pop the question right then and there. A number of international airports have high-end jewelry shops within their terminals.
Tokyo's Narita Airport, for example, has two Tiffany store locations, in Terminal 1 and Terminal 2. Heathrow has one as well. And here's one obvious bonus of making this life-altering purchase during your layover: You could potentially save a bunch of money on the diamond since airport purchases are duty-free.