In the opening act, Marcy steps in to the cabin's main bedroom and remarks on how much she likes the cute little room, with its cute little bed, the [lovely] view from the window; and how happy she is that, thanks to the remoteness of the cabin, they can look forward to a nice fun vacation without anybody bothering them. The connotations of that last comment are overtly sexual, as she is already in bed with her boyfriend Jeff when she says it, and they are excitedly getting undressed to have sex.
Cue the predictable intrusion of not one, but two of their friends, who interrupt their attempt to have an intimate moment together. Looks like Marcy spoke too soon when she said that there'd be no one around to bother them. Fun gag.
Fast forward to the second half of the film, after the virus outbreak has turned the vacation into a tragic nightmare.
Paul discovers Marcy sitting in that same cute little bedroom, sitting on that same cute little bed (which she will soon be using in the manner she'd originally intended to use it), and staring out that same window at that same lovely view. Then, most importantly, she fulfills the final part of her original statement, by seducing Paul and sleeping with him, without anybody bothering them. Because Bert and Jeff have fled, and Karen is bedridden and dying in the toolshed; there's nobody left to bother them!
All Marcy wanted was a getaway where she could enjoy some carefree sexual release without being disturbed. In the end, she got her wish; but not in the way she intended.
by squickchick