Agape or (among other definitions) "unconditional love" does not require reciprocation in the way that eros does. It does not seek reciprocation in a quid pro quo manner. If it is the highest love, it may also be the most difficult to perform, partly because it does not seek reciprocation, partly because it may be roundly insulted and rejected, or ignored.

One does not "fall into agape love" the way one falls into erotic love. One has to strive to experience it. Certainly it requires engagement with others; any sort of love without engagement is just so much mental masturbation. People who play at having agape without engagement with others are very disappointing.

A Christian would probably claim that agape was a grace from god. A non-believer might consider it a grace without a source. One should seek to find one's way to agape. It has a central place in spiritual discipline, and it doesn't take the place of other kinds of love -- filio, eros, or storge (to use the Greek terms) and it isn't incompatible either. One can be engaged in filio and eros without abandoning or compromising agape.

My song is love unknown.

My song is love unknown,
my Savior's love to me,
love to the loveless shown
that they might lovely be.
O who am I
that for my sake
my Lord should take
frail flesh and die?

He came from his blest throne
salvation to bestow,
but men made strange, and none
the longed-for Christ would know.
But O my friend,
my friend indeed,
who at my need,
his life did spend.

Sometimes they strew his way,
and his strong praises sing,
resounding all the day
hosannas to their King.
Then "Crucify!"
is all their breath,
and for his death
they thirst and cry.

Why, what hath my Lord done?
What makes this rage and spite?
He made the lame to run,
he gave the blind their sight.
Sweet injuries!
Yet they at these
themselves displease,
and 'gainst him rise.

They rise, and needs will have
my dear Lord made away;
a murderer they save,
the Prince of Life they slay.
Yet steadfast he
to suffering goes,
that he his foes
from thence might free.

Here might I stay and sing,
no story so divine:
never was love, dear King,
never was grief like thine.
This is my friend,
in whose sweet praise
I all my days
could gladly spend.
Words: Samuel Crossman (1624-1683), 1664