Coping with being happy and overcoming the issue of happiness occurs several times in grief. While many people write about grief, few discuss how to cope with happiness or that the issue has more than one stage.
The first stage of coping with happiness gets at least some notice and discussion. This stage is the disruption and confusion that occurs from experiencing joy in the brief appearances it makes. In the black and white world of gray grief, joy is like an unnatural splat of color. The initial break throughs are usually sudden and unsettling.
But, like green shoots of growth in the gray of Spring, they are really a promise of life. A little warning and people are ready to accept these flashes as positive motes of light in darkness.
Next comes survivors guilt tied into happiness. Especially during layoffs, people will have survivors guilt for having a job when those around them were fired. Or a surviving child will feel guilt for still being alive or for having a happy moment when their sibling died and their parents are devastated. In every situation of grief and loss, those who remain may feel guilt and sorrow at feeling happy.
Finally comes accepting happiness for itself. It is not betrayal of sorrow. It is not a harbinger of disaster (many will remember their last period of happiness ending in the disaster that brought them grief and have learned to associate happiness with disaster striking).
Acceptance is just a coping mechanism. Accepting happiness is something else, it is a return to life.
Related essay at: http://ethesis.livejournal.com/ (my first post there of any meaning, may be my last as well).