I agree with you that God is calling us (as His Church) ... to the fullest expression of love ... for Him and for our fellow man.
Yet that love can be lived out in its fullness ... and it can be summarized in a brief statement such as Vicomte13 suggests.
Neither type of expression invalidates the other.
As you have suggested, the tpye of love God desires to share with us ... can be compared to that which a faithful husband and wife share.
And yes, ... that love is expressed in its fullness as the two come to know and cherish one another more and more through the years ... and in sharing every facet of themselves with the other.
But that love is also quite nicely summarized during the wedding ceremony with the simple phrase ... "I do."
It is upon such a simple declaration of love ... that the two ... are joined ... as one.