I believe fibbing by omission only has a place to play regarding gifts or intended pleasant surprises.
In all other situations, it is simply being devious-in some, life shattering.
My Mother abandoned our family when I was barely seven. Many years later, when I had my first child-I reconnected with her. Unknown to me, she and my MiL had formed a friendship with the main intention of my mother lying about me. This created a tension with my MiL, of whom I was fond, and I never understood why. I now see that there were plenty of occasions that lying by omission took place. The relationship with my Mother collapsed when my children were small but her friendship with my MiL continued until eventually, I was told by a stranger that my mother had died. I then learned my MiL had been in touch regularly with my mother for 24 years, attended parties and was even given furniture by her. MiL knew that my mother had died six months before I knew so both my sister and I, could not even find closure by attending her funeral. The saddest part of it was my MiL had told my mother that my sister was suffering from cancer and not even then did she have the parental instincts to reach out. So in that instance, lying by omission caused the most dreadful pain. My husband point blank refuses to talk with his mother now as he does not have any trust, this too has had an impact.
