I cannot imagine there will be many raised eyebrows over this in Denmark.
That Marie is going to a nightclub with friends is something basically only royal watchers will even notice.
Most will simply think: Great, Marie is having fun with her friends. Good for her. And that will be it.
Unless she is dead-drunk, completely stoned, stripping while dancing on a table or attempting to grope every man in sight, this will in no way be percieved as dubious behavior.
She is surrounded by friends in a public place. She was going to a night club, where many of the group of people who aqquiant the DRF go. No doubt she would have met quite a few at that club, whom she already knew.
She was basically socialising with the same sphere of people, she is otherwise socialising with, formal and informally, when she is Copenhagen.
Should Marie start to get drunk, her friends, if they are true friends, would intervene. Should anyone try to hit on her or there should be other kinds of trouble, people would form a protective screen around her, as they have in the past with Frederik, who was a very frequent guest at all sorts of nightclubs.
The Danish jet set after all only consists of a few thousand people in total and they have a tendency to mingle with each other in the same places and as such they more or less know everybody else.
From an infidelity point of view, I'd say that a nightclub is about the safest place la Marie could go in the eyes of Joachim. Marie could hardly have a fling with anyone there without that fact being known to him within a few nanoseconds. He would have much more reason to be concerned if she went to a private party, away from the public glare. Or Marie "just going shopping with some friends".
But I have seen no hints whatsoever that Marie and Joachim's marriage should be strained, nor have I ever heard about Marie being the least bit "loose".
ADDED: According to MSN Starlounge
http://msndk.starlounge.com/index.cfm?objectid=82521 Marie went out with a few of her friends. They arrived at the night club at around 23.00 and left again around 01.00, where she was escorted to her car. Presumably either to drive back to Amalienborg or being driven back. (PET usually don't accompany Marie and Joachim). At the club she met Niklas Bendtner, the boyfriend of one of her friends, Caroline Fleming. He was there with some friends as well.
She was seen dancing and having fun.
It may be a cultural thing but here in DK, there is a good deal of respect around what people do in private, even in public places. Yet. The magazines are hesitant to write too detailed about it as the readers have a tendency to react against it.
A number of years ago a government minister dragged his mistress to a public event. Editors admitted later that it was a boderline issue, but they didn't write about it. That minister's sexual exploits was considered a private matter.
In my opinion it's not only her right to go out with her friends, it's beneficial.
Now, Mrs. Muhler is not a princess but she often go out with her friends and I would feel pretty silly if I insisted on going with her to say, watch male strippers.
The bottom line is of course that if she is having fun, I'm happy
And she has so many opportunities to have a fling anyway, that I cannot prevent it unless I locked her up. - And so have I. Opportunities that is.
Where were Joachim? No idea, perhaps he was watching the world championship in snooker, like me, completely oblivious to the rest of the world. And la Marie could A) watch it with her husband, while yawning her jaws to shreds or B) go out with some friends.
(Or C) like my dear counterpart, text her thumb to pieces while finding a sadistic glee in commenting on the utter pointlessness of two adult men using a stick to hit coloured balls with
).