From Dawn Eden comes this reflection by Fulton J. Sheen on love:

EVERY PERSON carries within his heart a blueprint of
the one he loves. What seems to be "love at first
sight" is actually the fulfillment of desire, the
realization of a dream. Plato, sensing this, said that
all knowledge is recollection from a previous
existence. This is not true as he states it, but it
true if one understands it to mean that we
already have an ideal in us—one which is made by our
thinking, our habits, our experiences, and our desire.
Otherwise how would we know immediately, on seeing
persons or things, that we loved them? Before meeting
certain people we already have a pattern and mold of
what we like and what we do not like, certain persons
fit into that pattern, others do not.

When we hear music for the first time, we either like
or dislike it. We judge it by the music we already
have heard in our own hearts. Jittery minds which
cannot long repose in one object of thought or in
continuity of an idea love music which is distracting,
excited, and jittery. Calm minds like calm music: the
heart has its own secret melody, and one day when the
score is played the heart answers, "This is it."

So it is with love. A tiny architect works inside the
human heart drawing sketches of the ideal love from
the people it sees, from the books it reads, from its
hopes and daydreams, in the fond hope that the eye may
one day see the ideal and the hand touch it. Life
becomes satisfying the moment the dream is seen
walking, and the person appears as the incarnation
of all that one loves. The liking is instantaneous—
because, actually, it has been there waiting for a
long time.

Do read the whole article. It's not terribly long, and well worth your time. His explanation of love at first sight is fascinating and raises the importance of proper formation. If, as Sheen writes, our concept of "the one" is formed by "our thinking, our habits, our experiences, and our desire", how important it is to ensure that those formative elements - including the example of parents, teachers, and friends - create a solid foundation!

He continues with a beautiful image of marriage as preparation for Heaven:

With marriage and its ripening with the fruit of love,
there will dawn a new understanding that everyone
carries with him a blueprint of the one he loves, and
that One is God. The other partner then is seen as the
Lord's John the Baptist, preparing the way and making
straight His paths.

So, not only should our interior concept lead us to one who fulfills the ideal, but ultimately, that idea should also lead us on to God. It's common to hear that spouses must lead one another to Heaven, but it is a bit different to hear them compared to the forerunner. Spouses are not the pinnacle of relationship, and so far from the perfection of God that they are not even worthy to "loosen the thongs of His sandals", but rather, it is their calling to prepare the other for God.

(Incidentally, I love the image of the "tiny architect" inside us; it brings to mind those old animated educational videos)