Another possibility: Luca was Vito's principal assassin, and he didn't want to be reminded of the "dark side" of his criminal empire on his daughter's wedding day.
Ntra la porta tua lu sangu � sparsu,
E nun me mporta si ce muoru accisu...
E s'iddu muoru e vaju mparadisu
Si nun ce truovo a ttia, mancu ce trasu.
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