The only thing worse than gf damage is wife damage (did the same thing to my 02).
These bumpers are made of tough stuff (urethane), and I'd be surprised if it couldn't be sanded out and repainted - though a professional job at a shop will run you about $100 - $500 (depending on extent of damage and whether or not they remove and repaint the whole bumper). Can't tell the extent of the damage from your jpg, but if it's limited to the lower lip below the mold line, I'd be tempted to just have the shop sand, fill and spot paint that area. Good job would be indetectable and much the cheaper alternative.
If you were planning to add an aftermarket spoiler, now is the best time, of course - and it might indeed cover the damage - be sure to examine carefully the overlap of the new part when making your choice, if this is the case. Whatever aftermarket spoiler you pick, most of them will require painting, which will cost at least as much as the repair, etc, etc.
Face the fact that the gf or wife damage to our cars is the price we pay for having females in our lives. My advice would be to be kind and gentle (unless you're ready to change gf's anyway) - which will make her love you all the more.
Next time if could be you who makes the mistake. Be big about it.
"You can never be free until you let yourself go."