Stop being worried about coming home. You have your incredible girlfriend and at least 90% of your efforts can be concentrated on helping her adjust to life in the States.
That being said, you should know that I've said "mulţumesc" in at least 10 different situations. My family is really tired of me asking "ce" when I cannot hear them, and I had a dream in Romanian the other night.
Get ready for the ridiculous amount of entertainment options, and be prepared to find very few of them interesting. The amount of English sinage is probably going to overwhelm you. You'll feel a little bit like Jim Carrey in "Bruce Almighty" when he can hear all the prayers- suddenly everything you hear is comprehensible.
Prepare yourself for getting upset at the grocery store when you spend $20.00 and they try to send you out the door with 8 bags. Try to remember that non-Romanian stores do not accept Romanian currency of any kind, and you'll feel like an idiot when you do it for the third time. You might forget that you can call and text people now (btw... will your number be the same?) Also, they have ice in America and they'll give you water that doesn't come in a bottle without going three rounds with the wait staff.
That's all the trivial stuff. I'll write the next part as if you didn't have your own Romanian throwback. You'll be sad. Depressed even. Everything at home looks good to you, but all in a Romanian light. You'll struggle with comparing everything to what you experienced there, what it's like there, what you saw there. You'll want to see everyone you can, and no one at all. You'll experience an insane desire to connect with people and a deep disappointment when you realize NO ONE knows what you are dealing with. They'll pretend to care while you pretend that you aren't thinking about the life you just left. You'll both try hard and fail. You'll scheme about going back even though you know you won't. You'll feel both alone and too close to everyone at the same time. If you are me, you'll cry when you see some of your best friends for the first time. You'll be happy and sad and confused and inexplicably angry at times. And you'll be tired.
And then you'll call me. Because I'm in the middle of it too, and it's a lonely place.