Paperback from the 70s or 80s. It might have been part of an Adult themed series. (much like the Longarm western series) But I am not sure.
A Couple on an low tech farming type planet head out in a field/meadow (pretty sure it newlyweds fooling around, or one had been away for a long time so they were just getting back together) A slaver spaceship lands to abducts them. (The man might have fought back, and gets killed so they only get the woman, or he was killed very shortly after getting them on the ship)
Specifics I remember:
Initially the woman did not speak the same language as the people on the ship. (But she does quickly learn it in some Sci-Fi way as opposed to months and months of learning)
After they get her on-board, The Captain orders the crew to feed or inject the woman full of drugs & aphrodisiacs so she is an eager & willing participant as the crew gang rapes her. But when the drugs wear off she vividly remembers the horror of the experience.
Later in the story she somehow gets the upper hand and takes over the ship killing most of the crew.
While she was killing everyone, one of the crewmen (Eng? Nav? XO?) tells her he did not want to do any of it (killing her man and raping her) Doesn't she remember him saying "something in a foreign language" [either to the captain, or to her, as he was taking his turn] She does remember him repeatedly saying those words during the gang rape, and now that she knows the language, knows that he is telling the truth and the only reason he did it was the Captain threatened to kill he if he didn't. So she lets him live. (I think he then assists her in running the ship)
Doing Google Searches, one possibility I came up with is it might be part of John Cleve's Spaceway Series. But I cant find much more than single line descriptions of the some of the books so I am not sure if its one of those.