Have you tried closing the bedroom door? Making sure, of course, that no feline ninjas lurk beneath the bed or behind the curtains or…well, just clear the area and secure the perimeter. Don't forget to equip yourself with high-caliber earplugs.
Or you might try bribes. Cats are suckers for snacks. Try to find one that doesn't smell too much like aged tuna, and keep it in a secure location. Do not—repeat, do not—keep kitty bits in your pocket. Cats will climb you like a tree.
Catnip, strategically stashed in, say, the cellar, could keep them zonked for minutes at a time. Long enough to hit the target? No wonder she's got cats!
But these are merely battle tactics. The first thing you must do, PW, is get your head out of the kitty litter and see that cats are the least of your problems. Cats are not your enemies. Cats are your girlfriend's allies.
In other words, sweetie, what have they got that you haven't? Be honest. Do you have muscles of steel and (forgive the analogy) catlike agility? Do you have velvet paws and a tongue that rivals the Swiss army knife for functionality? Do you purr and rub her ankles, even when PMS makes her act—and look—like Godzilla?
Face it. If you can't outflank a few felines, regroup. Consider your strategic objective. As your advisor, Auntie strongly recommends that you pull out and set your sights on a new target. And for heaven's sake, go find yourself a girl who's allergic!