1st --> Your gf should keep her dog in her place.
2nd --> Take that dog to the veterinary NOW, unless you REALLY want to see your gf in tears.

WTF? How the hell could this had happened? Somebody fucked up dude... period. Doesn't matter who, this was a major fuck-up.

For feeding time, try separating them. Take your gf's pup and feed her inside the house... when she's done, put her outside.

WTF? Go to the vet NOW!