biggest mistake that men/women make in their relationships?

Whether it is sexual, emotional,
physical, or intellectual once you
are unfaithful (or your spouse is)
there's no getting back to where
you once were. It will never ever
be the same no matter what
either one says. It will always
linger in the darkest corners of
the mind. Always.
Whether its one always having
that thought in their head of
their spouse cheating, or the
cheater always knowing that they
got away with it before and how
they could do it again.
Inability to talk about sex;
different attitudes towards
money; lack of skill to settle
differences sensitively.
None of this Mars and Venus
rubbish, please. I think that one
of the biggest mistakes is the
inability to talk frankly about sex
(I could go on about this in huge
detail, but will spare you).
Another mistake comes from
different attitudes towards
money; and another one is the
inability to handle difficulties
sensitively - for instance sulking,
the 'you are ...' statements that
make generalisations from a
particular incident, and what I
call 'sock drawer' arguments:
that is, there's one difficulty to
be settled but either party starts
to add 'and another thing is .....
you don't tidy your sock drawer.'