The waiter isn't being rude when he leaves you alone to eat.
This phenomenon isn't unique to Italy, but it bears mentioning because it catches so many off guard.
Where I live, waiters come check on you 90 seconds after deposting a plate in front of you, wondering if "everything is okay" before you've had a chance to even take a bite. They'll check on you a few times during the meal, and then when it looks like you're close to being done they'll leave your bill on the table for you to take care of at your convenience.
In Italy, after your meal is delivered, you may not see the waiter at your table again until it's time to clear your plates. And when you're done with your meal, after coffee or dessert or whatever your final course was, no one's going to come by with a bill without you specifically asking for it.
This is not the waiter being rude. This is the waiter letting you enjoy your meal and your dinner conversation for as long as you want. Restaurants in Italy are not looking to "turn over" tables every 1.5 hours - once you sit down, that's it, that's your table. It's yours as long as you're there. So when you're ready to leave, you just flag down your waiter the next time he passes by and say, "Il conto, per favore." You'll get your check, and you're not being rude for asking for it. Oh, and don't forget to bring cash.