At start of r/s... having sex often is normal, but tend to wear
down over time.. imagine doing the same thing time and time over
again with the same person.
Like what u said, she is tired or hasnt got the mood, so u know
where the problem is... just try tackle this 1st. women are
creature of feeling. Try something new each time to keep the
excitement and spark alive like u all once share. Try sharing part
of her work load like taking care of the kid for her, doing the
house chores, etc and let her rest, or send them away for a while.
Try adding toy to the fore play. Try to understand her need and dun
be shy to ask what her fantasy are and maybe both of u can act it
out. Try having sex at different location or different time. Maybe
she need a break from her normal life, bring her on a second
honeymoon?
Basically, it is simple, find out what her need are and where the
problem are.... If both of you are married, I am sure if u
satisfied her need, yours will be satisfied as well. If not, there
could be other underlining problem which u duno.