Cats can carry a grudge for a few days. After that, they start to forget what they were mad about. Like most of us.
My girlfriend's cat very explicitly snubs her for several days after she comes home from a trip-- even though there are other people in the house, "My Human was bad and left me alone for the weekend."
If the cat didn't know you very well -- and especially if you smell different for some reason -- you may need to go through the exercise of making friends again. It should go faster this time. (And even if it remembers you well, a bit of bribery helps soothe hurt feelings.)
Meanwhile the standard rules apply. Let the cat come to you when it's ready; don't chase it, don't stare. Try not to move too quickly/suddenly. Sitting still for a while -- with a book, perhaps, or TV, or just chatting/cuddling with your girlfriend -- is less threatening than standing up or moving around,and lets the cat decide how close to approach when.
If your girlfriend is still on the cat's approved list, and the cat is being held by her, you may be able to come over and pet it a bit without complaint; that both makes the cat feel a bit more protected and gives it an even better chance to try to make you jealous by making a fuss over the other human.