This ceremony seems to originate from a Saint Milis legend.
Once upon a time, before heading to certain death, he gave a necklace to his most beloved one.
The most beloved one kissed Saint Milis on his forehead, and wished for his return.
When Saint Milis was in dire straits, the most beloved one offered that necklace to God.
God, touched by the exquisite necklace and the most beloved one's love, saved Saint Milis.
That was the legend.
Discerning fact and fiction in this world is difficult.
So that might have really happened.