Another American who was planning on going to Ireland to do a PhD - but eventually decided to stay on in the US to do it there instead.
http://friendofmysoul.wordpress.com/2009/08/31/108/
It was a hard decision - but as the writer says
"I don’t doubt my decision in even the slightest degree, but I have begun to scheme about getting back there next year, and wishing I could go tomorrow. Just for a week or two. Or three"
Maybe she will be back for good one day?
Good luck to her in whatever she decides to do.