Well you assume your girl isn't going to be happy if you look at other girls. If you think about it, no harm can come. Do it anyway and if she has a problem...well that's your decision.
You say you get jealous with her guy friends. Damn, if that's not neediness, I don't know what is. You're better than jealousy. No person should subject themselves to such emotions.
Why do you hope to supress a natural desire that can do no harm? It's not like killing someone. I therefore assumed that since you are supressing healthy natural desires, you have replaced it with a need for her validation. Like if she rejected you, I can imagine you'd be crushed. How WOULD you feel if she one day said "You know what? No more." I think you'd be crushed with your current mindset. That's no way to live
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Develop internal validation. You don't need other people to complete you or make you happy. They can only increase the sense of happiness already inside of you.