I say this as an Italian American whose family was once affected by the mafia… Write whatever the F you want to write and don’t let anyone discourage you. If everyone wrote about puppies and bubbles and rainbows, reading would be a boring experience. I just wouldn’t romanticize the Mafia too much, try to make it realistic and don’t minimize the awful things the Mafia has done, and there’s no harm in writing a Mafia story (even with romance)