I'm not sure what you mean by "whine" but my car has what sounds like a vaccum leak that comes and goes.
Last summer it would happen maybe once or twice a month and was only noticeable when I got close to 3k rpm, about when I would shift to the next gear. If I floored it the sound of engine drowned it out above 3k. I replaced the PCV valve and it seemed to fix it.
It has since come back and is noticeable anywhere above 2k rpm, even at full throttle.
It may actually be two different sounds as before the car ran the same with or without the noise, now the revs seem to drop a tiny bit faster when I hear it which can cause a few jolts when shifting before I adjust.
I'm under the impression that it's a pulley/it's bearing going out.... now that I think about it, maybe it's my alternator. Wow, I type a bit too much at times

If your gf's symptoms are similar to my problem last summer you could check for vaccum leaks and maybe just replace the PCV valve just in case since they're cheap and better safe the sorry on that.