We leave Holland this Saturday for England, where we will be staying with some of my family. I'll feel a lot "safer" I think when we get to England, as the opportunity to go out and date will be eliminated until we go home (a week after that)
Is it the closing off of the possibility of him dating that will make you feel safer, or being with other people who also care about you? Or is it both?
He would really like me to meet her. I've been stubborn though. Part of me is scared that he only wants me to meet her, just so that I can be the one to explain our poly relationship. He said she backed off a bit when he said he was married, and he just doesn't know how to go further with her. He also has the added burden of having to be careful ethics wise, because this is another employee. But he also says that she still seems interested, just very hesitant. But I can't imagine sitting with her, being so shallow and petty (me) and hating every minute of a dinner.
It seems to me you're being awfully hard on yourself, basically dismissing yourself as shallow and petty. Even if it's true, give yourself a chance to outgrow that. Try something new and daring . . . like meeting someone your partner likes.
If you don't meet her, you're likely to make a lot of assumptions about how wonderful she must be, how much you pale in comparison, and so on. Your imagination will have free rein to cook up worst case scenarios.
If you meet her, you'll at least be able to get a better sense of what she's actually like as a person, and what, in particular, your partner might be drawn to.
I mean, if your partner finds her interesting, it may be that she's a genuinely interesting person, one it would be worthwhile for you to know on your own terms. If she's native-born Dutch, she might also give you some connection to the culture of the place you've been visiting.
Also, be aware of how your partner is feeling: if he's hesitant, confused and fearful, he needs your support, attention, and advice. It's a strange role to be in, I know, advising your partner on how to proceed with a possible new relationship, but it can have the paradoxical effect of strengthening your partnership.
(My wife and I have taken turns advising and consoling one another. I've been living through an ethically fraught, non-reciprocated crush for some time now; she's had one promising relationship go down in flames. As that relationship first developed, it helped me a lot that I already knew the guy in question, and could see why my wife was interested.)
I've thought it would be better to date independently, and invite to meet each other when the time is right. I don't like the idea of us appearing as one entity and not two separate people.
Well, yes, but that doesn't mean you shouldn't meet her, especially given the short time span involved. Maybe you could meet her separately, over coffee? Even if all three of you meet, you can establish your independence. Dinner might be a bit heavy. Maybe something more casual?
Sightseeing?
(That might be a good idea, actually, though it would probably be best not to ask her to show you the red light district . . .)