Are 16-year-olds allowed to go on holiday to Italy with their 18-year-old boyfriend?

Hi, I (18 years old) would like to go on vacation to Italy with my 16-year-old girlfriend for about 4-5 days. Does anyone know what I need for that? Or, if we want to stay in a hotel, do I need a consent form from my girlfriend's parents? Or something similar? Or is it not…