life's noblest lie:
Amor omnia vincit
...it hurts.

I will not attempt to argue with the good senor on his point that I would not have remarked thus if I had known love. I have and it is reflection on this love that lead me to this statement. But that does not express the reflection in its entirety (neither will this though...)

In the end it all depends on the direction one is looking from... from the perspective of mortality and change and imperfection it is true. Men change and thus necessarily so does their love. It waxes and wanes, finds new direction and looses intensity. It is everything man is, it reflects him in all his faults, it is imperfect - it dies. It is the doom chosen for all human things at the moment Adam took the fruit from his wife's hand.
However, in the end, that is not solely what love truly is. From the perspective of the immortal and unchanging and perfect, it is perhaps our closest conception of what God is in Himself. It is all that St Paul described- patient, kind, bearing all things, believing all things, hoping all things, enduring all things, never failing, never ending. This is what man was intended for at the first creation and lost in his fall. In the re-creation of the Cross, it is offered to him again but this time with a requirement attached. Man must enter into the sufferings of the Cross, sharing in its the pain and sacrifice in a spirit of submission and willingness and humility. Man's love becomes his cross, drawing him in two contradictory directions, toward heaven and across the earth. And even then the fullness and perfection of love desired cannot be achieved in this life, it is only seen from a distance as Moses saw the Promised Land from the peak of the mountain but could not enter into it.
Man, acutely aware of his passing-ness and imperfection, craves the unchanging and the perfect. And every fiber of his being tells him that this desire ought to be satisfied in goodness, truth, beauty, and most especially in love. It could perhaps be described as his recognition of what was lost in the fall. Man, being the mixture of the mortal and mutable with the immortal and perfectable that he is, is neither able attain the love he desires in this life nor condemned to the merely mortal affections proper to the flesh. He is given both, mortality with the promise of perfection. Change and death are inexcapable and are yet able to be overcome.
Hence I feel justified in saying that man's love fails - it does. But that is not the end of the story because to be true love it must be God's and that we are assured never fails.