Squats and deadlifts target the lower body, not upper, which is what you need to focus on in order to develop the arm strength to carry a person like that. Bicep curls, pull-ups, overhead shoulder press, rows, bench press...these develop upper body strength.
That said, lifting a person is not at all like lifting a rigid weight. People are soft, lumpy, amorphous--and a lot more difficult to grip and carry, unlike a barbell. So you'll need to practice on a real person in addition to weight training. There are a lot of stabilizing muscles that you'll engage when practicing on a real person as opposed to a barbell; however, you will need to develop enough strength in the primary muscles first.
And of course, it all depends on how much your girlfriend actually weighs. A 110 lb. person will be a lot easier to work with than a 170 lb. person. It also depends on how much she helps you out by holding on to you. A person who goes limp is a lot harder to carry.