So, that pretty much left me considering the classic Straight razor, more ominously known as a ‘cut throat’. Mother Earth News have a lovely piece on these, that even includes detailed instructions and quirky illustrations on how to get a baby smooth shave that lasts the whole day through, while keeping your throat intact! I suspect this is your best bet, Mark. Combine one with a natural ingredient based shave cream, say something of the Tom’s Of Maine ilk, and your girlfriend and your planet will both thank you.
For those mere mortals choosing not to embrace a Straight razor, might I suggest simple eco-steps like: using a refillable blade razor, shaving less (maybe try a beard!) and/or just using water as your lubricant.
And if you really find yourself stuck, then use whatever razor works to keep your relationship cuddly and continuing. Sweat the small stuff less, in this one instance. Insulating your home, catching more public transport, eating one less meat meal a week, installing compact fluoro lights, avoiding that plasma TV purchase, will all help our little blue/green ball much more than whatever shaving regime we guys (and girls) opt for.
PS. I once posed this very dilemma to some uni students, as an ecodesign problem solving exercise. One solution offered, was for guys to ‘wax’ their stubble away. Maybe it was the look of horror on the faces of male students, that stopped the other half from deciding such an idea would meet with big commercial success!