If you're having an open relationship with your gf than It's a normal thing but If your relationship is normal, you shouldn't tolerate these things. Even if your relationship status is open you have to follow certain rules and regulations.
I'm currently in an open relationship and I found my current partner in a biker club. But open relationship or any other type, you've to follow some rules and recalculations to make it successful. Open relationship rules may seem like an ordinary thing as there are no strings attached but after keeping these in mind, you avoid all kinds of difficulties and tensions. Trusting each other, avoiding common friends. keeping the relationship secret are some of the rules that are necessary for this kind of relationship. So If you both want to have a open relationship, just follow these
open relationship rules.