The refrain

Of "Flightless Bird, American Mouth":

Have I found you? 
Flightless bird, 
jealous, weeping 
Or lost you?
American mouth 
Big bill looming

Yet, there are many instances of this song that say "Wedding Version." It is a lovely song, but also very sad, so I'm not sure what makes people choose this as a wedding song? Unless it's in the tradition of old-fashioned, arranged, give away a girl as chattel...Or do people associate  matrimony with sadness and pain more than they realize?