No?

A thread is spun;

a broken one:

not the way it should have been.

Off-key song;

something's wrong:

not quite the way it had been seen.

Nothing's amiss,

yet something is:

what, exactly - can't put a finger.

Like a dish not ate

or a friend not met,

yet whose taste and thought still linger.

What was not

can't be forgot:

you just can't miss what never was.

An illusion,

or delusion:

how can effect be without cause?