Depending on who happened to publish your edition of the Bible, the heading on the page that contains our text might say Song of Songs or Canticles or Song of Solomon. So saying, it is not generally thought that King Solomon was the author - granted he was a lusty fellow with 700 wives and 300 concubines, but that in itself, in my view, would mitigate against his authorship (when would he have had time?). More likely, Solomon's name became attached to the book in some sort of dedication. The original-language title of this book (Song of Solomon) is a Hebrew way of talking about the finest song just as "king of kings" means the greatest king. Somebody, somewhere, way back, thought these love poems were the best of the bunch.
Not only the passage given above but the whole book is an ode to …