Currently on a trip to Europe, through EWR-DUB, and trying to check my return flight. My confirmation number doesn't work with my name, only my girlfriend's. I call them up.. they split us into two seperate itineraries, so now I can't move her into preferred seating / etc.

I know they can't put them together, and I know WHEN they split them - we flew on an earlier flight from home-EWR due to weather concerns of our original flight - so we both went standby on the earlier flight. WHY did they split it into two?