I had a book of superstitions when I was a kid that explained it. People used to think that stepping through the doorway to a new house with your left foot first caused bad luck. If I’m remembering right, women couldn’t be trusted to put their right foot first, so men started just carrying them over the threshold. I can’t find anything to confirm that, though.
ETA: I owned my place for a couple of years before **Least Original User Name Ever **came along.
That is exactly what I’ve read too. But it’s the first step over the threshhold in your new life together that is crucial; otherwise, you’d have to be carrying her over each time. Don’t want to get started “on the wrong foot,” heh.
