iserith
Magic Wordsmith
For me, it's even more about the real world issues. DM wants to wrap it up. Scheduling issues. Incompatible player preferences. I wouldn't have gone past session 1 given the latter two conditions (provided they were discernible), leave alone done a whole campaign. And it's not likely the DM is going to get a bad Yelp review for wrapping it up when it needs to even if the characters fail to achieve their goals. Capturing them and playing out some kind of escape only keeps this game going longer and allows the real world issues to persist.Well it could be something as simple as the the Barbarian's hunch being confirmed by faint tracks coming from the direction of the circle.
BUT the more I'm reading the more I tend to agree with @iserith. You're looking for an endpoint, this provides one - one way or the other. And frankly, if the party gets caught with their pants down, well that's mostly on them. Long rest anywhere near enemy territory is dangerous and needs to be thought of as such!