In the introduction to Deus Caritas Est, Pope Benedict XVI writes:
...I wish in my first Encyclical to speak of the love which God lavishes upon us and which we in turn must share with others. That, in essence, is what the two main parts of this Letter are about, and they are profoundly interconnected. The first part is more speculative.... The second part is more concrete....
It would be a mistake to read him as meaning the first part is merely speculative, that it deals with ideas without practical application.
I don't know that anyone has made that mistake, but it's easy to do, I think. Reading something like, "God loves, and his love may certainly be called eros, yet it is also totally agape," a body might be excused for thinking, "Oh, ah?" Theology, especially when written by a theologian, can seem awfully abstract and removed from the practical questions of what should be done. Heck, we even distinguish between fundamental theology -- the stuff no one understands -- and moral theology -- the stuff no one wants to hear.
Still, a measured reading of the first part of the encyclical will show that you don't have to wait till the second part to be faced with practical matters. Consider this passage:
The Eucharist draws us into Jesus' act of self-oblation. More than just statically receiving the incarnate Logos, we enter into the very dynamic of his self-giving... [T]his sacramental "mysticism" is social in character, for in sacramental communion I become one with the Lord, like all the other communicants... Union with Christ is also union with all those to whom he gives himself. I cannot possess Christ just for myself; I can belong to him only in union with all those who have become, or who will become, his own. [13-14]
Is there a term more likely to convince someone that what he's reading has no practical application than "sacramental 'mysticism'"? Yet "I can belong to Christ only in union with all who belong to Christ" is not just a theological observation, it's a fact against which we must measure our own commitment to union with all who belong to Christ.
What the Pope writes about the Eucharist in the first part of his encyclical yields a number of quite practical results. So too with marriage, so too with love as we do or should experience it. These results are evident if we consciously seek both meanings of the meaning of his words: the conceptual content and the implications for our lives.