Wow, pretty rare to see straight (heh) talk on characters' orientations and preferences (the only other thing to immediately come to mind is THAT chapter in School Zone). Seems pretty obvious that Rei's gotten burnt before by coming out to someone and then things going badly. So she lies to everyone and herself that she's happy with current status quo, but almost admits she isn't, before "just kidding!"
Edit - oh right how old is she back home? She's an OL so in her twenties at the very least?