Outlander is a truly outstanding novel, but it is not a romance in the traditional sense. I don't want to spoil it for you, but it is certainly fair to say that this hero and heroine go through quite a few separations before the end of the book (let alone before the ending of the 6th book in the series, which has just come out and which is not the final one) and that some of them are pretty harrowing. But I wouldn't say the separations are unnecessary or don't add to the story, if that's what you mean by plot ruses.
You're also likely to find that finishing and enjoying Outlander has committed you to reading 5 more ~1000 page books, plus at least one more that Gabaldon probably won't publish for 2 or 3 more years. *That* might make you want to slap us around! :)