Have no idea about specific dates although I have noticed that there are international deals to be had which are usually advertised after Feb and prior to Easter.
My guess is that money has been spent on Xmas presents and holidays, school fees, rates etc. and people are gearing up for the Easter break so there is not a lot being spent on booking ahead prior and after Easter.
With Qatar airlines and other carriers whose clients may celebrate Ramadan, there is always a lull in seating capacity in the month prior as everyone gears up for the special celebrations at that time. I went business class to Europe and back in June this year from BKK and there were plenty of empty seats. The flight attendant told me that they are usually full but preparations for Ramadan were in full swing and people were not travelling as much.
I went Y to BKK with Royal Brunei and the whole airfare cost me AUD 3700. I stayed over a few days in BKK each way. Some people go Singapore with Y and then onto Europe in J. I loved the Dreamliner - great flying experience. JoyV