Can I masturbate to men while in a relationship with my girlfriend?

I'm a guy in a loving relationship with my girlfriend. She already knows I'm bi, and in fact, she was the first person I told. But, I've been watching porn since I was young, and now I feel guilty watching it. Is it okay for me to masturbate to men while in a relationship with my girlfriend? I've tried to stop watching porn completely, and she significantly decreases my desire, but I do get the urge from time to time. Is it wrong for me to occasionally satisfy my small desire for men? I love her with all my heart, and would never dream of being with someone else. What should I do?