The short (and unhelpful) answer is that I didn't intend to move here.
I came here for a long vacation of sorts (quit dev job in Ireland, swore never work in IT again, first stop on taking a year out to travel the world...).
I was at a point where I'd over-stayed tourist visa and was getting ready to move on and then I met a girl...
So it goes! I don't know why it surprises me, but a sizable portion of the expats here in Berlin originally came for a guy/girl.
Meeting a guy/gal is a major biological driver in life. Other than food/physical safety, what is more important in life?
An aside, but why did you move from Ireland to the US? I'm semi-seriously considering moving to the UK or Ireland, not out of any "argh america is literally hitler, i'm out" impetus, but to be closer to my girlfriend's family and for adventure.