This is a good, brief introduction and application of St. JPII's _Love and Responsibility_, for those who already have at least a basic Christian worldview. It was recommended to me as a book that would be particularly useful for people considering marriage (either as a single person discerning the general vocation, or as a couple preparing for marriage), and with the questions at the end of each chapter, I do think that is the audience for which it may prove most helpful, although the already-married looking to deepen their understanding of the state of marriage and move forward toward a stronger marriage would also find it beneficial.
I am still seeking a book that lays out the (strong, SANE!) Catholic teachings on love and marriage that does NOT require a Catholic foundation to relate to it: an examination of the purposes and benefits of true marriage, and the consequences of supporting or denigrating that, for individuals and the culture at large, from a purely "practical," "lived" point of view, that would not "turn off" those who either have wounds that result in aversion to "churchy" ideas and language, or who are simply so unfamiliar with them that they cannot yet relate to them. I can clearly see in my head how that book could easily exist, and would be SO helpful to SO many people in our deeply confused culture, but I have not found it yet. If anyone reading this knows of ANY work like this, PLEASE recommend it! Thanks!