I want to play non-spilt screen multiplayer with my girlfriend in the same room.

Hi, West. My name is Ron, I'm an independent advisor. I will be more than happy to help you.

What you will need to do here is to set your account as the home Xbox on your girlfriend's console by logging in to your account there and then doing the steps below.

Press the Xbox button  to open the guide.

Select Profile & system > Settings > General > Personalization, and then select My home Xbox.

Do either of the following:

Select Make this my home Xbox to designate the console as your home Xbox

Once you are done with that, your membership benefits will be shared to other profiles on that console. For your own console, you will just need to sign in to play games, make sure you don't set your account as the home Xbox on your own console.

Splitscreen is a bummer in multiplayer. If the original controller lags out or you leave the game, the splitscreen person loses everything. It's like they forgot to add a save feature for the spilt screen controllers. Highly recommend never playing multiplayer
on spit screen.

Online spilt-screen is one of the worst things to happen to multiplayer. Split-screeners are garbage and they ruin matches with their stupidity and lack of skill.

ok thanks guyz but i just asking can i play spilt screen without download stopping?

When my girlfriend and I game together, we do it on the same TV. However, this is only because the only game she plays is Left 4 Dead 2. So we split screen whenever we play. If you two will be playing separate games, I would do separate TVs side by side
so that it is easier to set up in terms of wires and connections and such (ethernet, router, outlets etc etc). Across the room might make it hard for wires.