[fluxrad]

I've lived w/ my girlfriend for ~3.5 years now. We split everything equally. If you get into "load balancing" then you're going to run into arguments about who's paying their fair share. What if she gets a raise, etc? Then you have to come back to and haggle for who pays what. Just split it down the middle.

If there's something you want, that she can't afford (in our case TiVo), then you can basically say, "Since this particular bill is above and beyond, I'll go ahead and pay it." but you should do your best to keep it 50/50.