Gooboy, there is something I don't understand. Why do you have to choose between the relationship and partying???
ok, having sex with other women might be a problem if you're in a monogamous relationship. But everything else, partying, going out with friends, travelling with friends, doesn't collide with a relationship! Your post sounds like your relationship is holding you back from enjoying your youth! Well I wouldn't want such a relationship... What kind of relationship are you having??? Having a relationship doesn't mean spending all your time with her or spending every evening at home holding her hand... I for my part don't see any problem in having a relationship and partying, going out with others and travelling around at the same time. Even when you have a relationship, you need your private sphere and time to be alone or with your friends anyway. So where's the problem?
About having sex with other women: you said you already had sex with enough women, so you know that's not the key to universal happiness.. I'm wondering what your reason is, because I get a feeling that you're a monogamous guy actually. So what's the reason for your wish? Do you need some positive female feedback and reassurance? In that case, work on your self-esteem. Or is it that you feel a bit caged in your relationship? I guess so, or else you would party and travel around freely. Or are you bored and want some adventures? There are many reasons you could have such a wish. Find it out and fix it. Leaving her and f***ing around will not solve your problem, as your problem is inside of you.
Or in the relationship too. But if this is the case, you'd attract the same in your next relationship anyway, so leaving is not a solution either.
Maybe there is something more general you're wasting in your life? You're not living what you could live now. What is it? Are you sure it's about sex with other women? Is it about partying? Why don't you do it then?? Is it something else? What? Maybe it has nothing to do with your relationship? Why do you think now is your "best time"? Every moment is your best time, even when you're 70.
Live more of what you really want to live, now, in your relationship, that's what I would say. Good luck to you!