WOW, sounds like me! I left my home in California and moved to Bristol England to live with my Brit husband. I've been here for two years but we are moving back to California this June.
I would love to write an encouraging post, but life here has been very difficult for me. Adjusting to how different England is, the weather, leaving my life, friends & family was rough. But I have grown to be even more independent and stronger. I don't like living away from my family and that is the main reason we are moving back. My husband isn't as close to his family as we are to mine and we both prefer to live in California than here.
Some things that are great about living here is the convenience of European travel, PIE's, cider, funny Brits, country villages, London, castles, and the best chocolate!
I would suggest that she get Skype so it's super cheap for you to call her. Instant messenger on the computer and emails have been a life saver for me...and my family! Cards, letters and care packages are what I live for! They make all the difference to me, the connection I still have with my family & friends.
It also depends on where she is leaving and where she is going. Some expats really like life here and would never move back to the US. Others have a hard time adjusting and prefer the US and eventually move back. I moved here solely to be with my husband (we met on Match.com!). I sold everything I owned and brought my dog over here, I didn't know anyone but my husband! It was a huge risk but I was willing to take it. I'm certainly glad I did because I married the most amazing man!
My Dad and I are very close and it's been the hardest on him. He calls me every other day and emails me constantly. He sends me care packages of my favorite things I cant buy here and many cards. He and I often talk about how parents don't have control over there children's decisions on where they live. He said my leaving was the hardest thing for him, but all he wanted was my happiness. And if that meant me moving here, he was happy for me.
Maybe what would be good for you is to talk to her family on the phone and get to know them a bit. I'm sure they have to know how hard it will be for you when she leaves. Remaining close and making the effort to do just that is what keeps relationships going, no matter how far we apart we are.