I guess you can't possibly understand it fully unless you've been in our shoes. I say "our" as in... those of us whose homes are overseas. Holidays are usually too short to go home - days like Thanksgiving and Christmas, when you're working, don't really mean breaks like they did when we were in school. Those of us who are here alone, even those with a significant other... when those holidays roll around, there's still a sense of longing to go home, to be with loved ones, to be with family.
How do you explain to someone that home is "too far" to travel to for the break? That home is a 20+ plane ride home? How do you explain when people look at you, confused? "Where is Taiwan again?" "Where are you spending the holidays?" "Does your family celebrate Christmas?" "Will friends be here to celebrate with you?" Well-meaning and caring questions from colleagues this morning. I usually don't let myself think about home too much, and I have adapted and grown in the five years I've been in the States since leaving Taiwan for school, but no matter how old I get, it is still hard around the holidays. I have lots of friends and am blessed to spend this Christmas break with one of my best friends and my fiance, but a little part of me still longs for home.
That feeling will always be there, I think... it will get easier, but it will always be there.