This is going to be a bit graphic. Anyone who is a christian best not read song of solomon. Also not read this.
Do you get morning wood? If so, then the problem is merely psychological and I think Magickal workings here would not be needed. It can't hurt - in fact, it can only help to compliment - the healing by doing workings. There was a thread posted about similar things which said about stopping masturbating for a number of days. It could be 1, 2 or 4 weeks. You might go for the 28-day one (and no, this is not "no-fap" nor "semen-retention"), and that includes not looking at porn and trying not to lust over others who you find sexy.
As for your girlfriend, you should do other-than-porn things. i.e. go more for the love-making and soft, gentle caressing and touching intimacy. For some people, what they do to their partner they either also - or simple just - want done to them. This may work; if not, then speak with your girlfriend and explain things that you've managed to be successful in this problem (no offence), not that you wanted to achieve these results, of course; or asking her to lay with you both naked closely, with zero oral, vaginal nor anal penetration, and just tracing her fingers up and down your back and chest and belly but not going too near your penis, balls and anus; teasing your nipples... being soft and gentle and sweet. It should be quiet, no or little talking, soft kissing, smelling her scent; if she smells nice, then taking a deep breath in of her scene; if she doesn't smell nice then doing it soon after she has a bath or shower; resting your head on her chest listening to her breathing and heart beating, deliberately avoiding her clitoris, vagina and anus, maybe teasing her nipples. Porn is for lust and to get-off quickly; you need to balance that out with love and closeness and bonding, then replace the porn with your girlfriend properly and nicely.
Do other things which tire you out. Be physical and exercise, go to a gym, move some heavy furniture - get a sweat on in a non-sexual manner. Make sure you're too tired to be horny when it comes to bedtime. After a number of days, the sexual energies would have built up a bit again. Psychologically, the expectancy of what porn "offers", with false promises, will have reduced a bit. More than a few days should be better.
I might recommend doing this above after you finish the 28-day abstinence. Trying it before the 28 days has elapsed might work, but instead after 4 weeks things should be more to a balanced level where you could achieve better results with it - sort of like building up the energies and then releasing them, like a coiled spring. Not only that, but I expect she would really appreciate that, as well. Let her know that you're not out for yourself, just to get your rocks off. Her pleasure is important to you, as well, and she deserves to know that this is true and that you mean it.
