As China's culture is the man to bring the two swallow to women in order to confirm the promise, because this species is considered to be a symbol of faithful love only one heart.
This is like Chinese culture Men will be presented to swallow two women to reaffirm the commitment because the bird is a symbol of faithful monogamous.
Which like the culture of China. The man will lead the swallows two to the woman to confirm the word because it is considered the bird is a symbol of loyalty, love one