Nowadays mourning seems to have dissappeared, the funeral happens and life returns to normal and the dead are rarely spoken of again. The bereaved are expected to pull themselves together and get on with life.
As a priest it is pretty obvious this can have pretty serious effects on people's psychological health, if there is no public outlet for grieving it tends to have a greater internal effect, it gets bottled up. I can't help but think a bit of black crepe might save a great deal on counselling fees.
Traditionally the Church gave a lead. Some places on the continent the catafalque was rarely taken down and black rather than green was the default colour of vestments.
I have been told that the current vesting options for funerals: black, purple and white were introduced to mark the gradation of different stages of mouning.
- Black the traditional colour for the actual Requiem,
purple for the months-mind, first anniversary etc.
white as was traditional for a child, and if appropriate to mark the end of formal mourning.
Apparently it was never the Church's intention to force white and the Glorias of Easterday on those who were in black, weeping and muttering the De Profundis.
Roman Christendom has a very interesting post on the traditional way to mourning, for how long:
for a widow 2 to 2 and a half years and a widow did not enter society for a year (although she could re-marry after 1 year and 1 day if financially necessary);
for a widower 2 years;
for a parent 2 years;
for children (if above ten years old) 2 years;
for children below that age 3 to 6 months;
for an infant 6 weeks and upward;
for siblings 6 to 8 months;
for grandparents 6 months;
for uncles and aunts 3 to 6 months;
for cousins, great aunts and uncles, or aunts and uncles related by marriage from 6 weeks to 3 months;
for more distant relatives or friends from 3 weeks upward.