How do I make sure my wife and myself are sitting next to each other on the trains.

The seat numbers are sometimes allotted in a strange manner. First, make sure you choose the same carriage. if there is a diagram of the train car, that may help, but the seat numbers may not be consecutive (54 and 58 may be side-by-side, with 55 and 56 opposite). If the diagram is a generic one and your train is configured differently, there is nothing you can do but ask to trade seats with someone in your section.

I'm having a hard time understanding the problem. Most regional trains don't have reserved seating. Walk down the cars until you find two seats together. Sit down. If the trip allows/requires reserved seats, pick two next to or across from each other. The seat numbers may not look right to you, but they probably are.

I've reserved seats for four and two that looked wrong but we're together. Seats in different cars I would worry about.

Which website are you using? What kind of train are you trying to book? Are you booking the two tickets as one transaction? Seats in different cars should not happen if you book both as one transaction---I have never experienced that.

[Edited] I have seen groups assigned in different cars (e.g., my group of three buying a same-day departure) and maybe this is your case, since I believe you're in Italy now. When that happened at a station ticket machine, I cancelled the booking and started over, but the solution was to spend another 10 euros per person for the next-highest class of service that had more space available. Do start out by booking for two together, not one at a time.

FYI- we just took 5 different trains over a 2 week vacation in France and Italy. I didn't pay any attention seats when I book, but was pleased to find we a always booked together and one 1 train across the aisle.
On two occasions, people knew they were sitting in our seats, but denied it and refused to move. One guy admitted it and only with insistence did he give up the 2 seats he was spread out in for our family. In the other, the conductor had to kick them out. Not sure if that is normal or just something we experienced.

Why would you wanna do that?

Last time I traveled on a Frecciarossa with my wife, she was on a seat across the aisle from me, and on my side I was sitting next and across 3 young gorgeous female models from Russia who were visiting Italy while in Milan for work. I had fun speaking to them the entire trip from Rome to Florence (and my eyes were happy too).

Why would you want to give up an opportunity to meet new people like that? You can see and talk to your wife when you are at home.

If you book on the Trenitalia site, select the "choose your seats" option. Then there will a graphic of the train layout and you can pick two seats side-by-side.

Roberto, stop trying to make me spit my coffee all over the keyboard.

hbrickson, that is really unusual, most people occupying other's seats will move (sometimes grudgingly and slowly); others are alert to the fact that someone may claim their seat and move quickly and politely.

I have only encountered the refuse-to-move person once, and I sat on the aisle armrest until he moved. The train was packed, turned out he had no ticket, and was put off at the next stop.

Way to go Zoe ! I would do the same !

And Roberto is right...part of the fun of travel is to meet people. We have found the trains and subways to be great conversation starters, even though we are not fluent in ANY language. Just the basic smile and our few practiced language lines.

I've never been placed in a different car, however. Not sure what I would do in that case - you just want your spouse or significant other to at least get out at the same stop as you !

My wife and I had assigned seats on the train from Florence to Milan but from Milan to Varenna we just had 1sr class seats but not assigned seats. I was able to pick seats for the train from Florence to Milan when I was booking them online

That is because the trains to Varenna are Regionali with no reserved seats.