Deja Vu

I saw it once,
I have no doubt,
but now can't place,
its whereabouts.

I try to think it,
time and time,
but what it is,
won't come to mind.

A word, a scent,
a feeling, past,
it will not show,
though how much I've asked.

And when it comes,
I soon forget,
this is how it felt,
when we first met.

There are things I miss,
that I shouldn't,
and those I don't,
that I should.

Sometimes we want,
what we couldn't,
sometimes we love,
who we could.

P.S - I refer a book.