Freedom in a relationship

Thank you very much for your detailed answer. I talked about it some more with her and she told me - after I reassured her that I love her and how great she is and nobody is as great as her - she told me that she would feel sorry I would experience great things with someone else and that she should be the only woman that experiences those things with me when traveling. She seems to be jealous of something like that, not sex.
It is kind of childish, I don't know. I am not sure if it is possible to reassure the partner that the love is so great that I can do anything with another woman - it is possible if the partner is already very mature, really, I don't know. At the same time, although your theory works for you, it might not work for other people. It would be great if it did, though.

I would have no issue with my girlfriend being jealous of me going over to Italy with another girl (especially one she didn't know), just as I would have no problem if she wasn't jealous - whatever she feels, her feelings are right for her, they are good, and they have a validity.

The issue isn't what she feels, but what her feelings mean to you.

If you think that it means you can't be yourself, then let her know, and go over. If you think her feelings are such that you would split up, and you don't want to split, you act according. If you think you would split, but to be true to yourself and your beliefs you feel you should be free to go over with a female friend...then you need to sit down and have a long talk, listenning carefully to both sides.

Then you have ones that are into BDSM, Auto Eroticism, Toys, being pee'd/poo'd on, bestiality, Swinging, and all sorts of other stuff...and for them it is right/fun etc

...the point being - we vary a lot in sexual nature, and it's not just down to morals.