It was a small but telling gesture that touched dozens of younger widows like Sandberg, who at 45 has two small children to raise in "this terrible, terrible club that no one wants to join," as one of her sympathetic Facebook commenters put it.
Grief need never be compared, but the "club" that is the Facebook exec's new normal includes members who feel set apart from older counterparts navigating the deaths of spouses much later in life.
Party invitations dwindle. Bereavement groups confuse and annoy both sides as older and younger grievers are thrown together. What about dating? What about sex? What about money and careers and managing the emotional toll on the kids?
"Some of the older widows would say things like, 'Well, you have your whole life ahead of you. What do you have to worry about?' We feel so out of sync. Suddenly we're the ones thrown out in the cold and our lives have been turned upside down," said Becky Aikman, who was 49 when her husband died of cancer.
Aikman tried a traditional loss group for widows, finding herself set apart from the 70- and 80-year-old somethings. She was kicked out after challenging the facilitator's approach and jokingly dubbed herself the "misfit widow," eventually seeking out five other young widows like herself to share a year's adventures for a book, "Saturday Night Widows."
At 60, Aikman said she and the ladies remain great friends.
Linda Feinberg was a therapist years ago in Andover, Massachusetts, when she met a young widow at a pool. They both had 3-year-olds and her new friend described similar treatment when she sought support:
"They said to her, 'You're young and beautiful. What are you doing here? You're going to get married again and be happy,'" recalled Feinberg, who went on to form a network of loss groups for young widows and write a book, "I'm Grieving as Fast as I Can: How Young Widows and Widowers Can Cope and Heal."
"There's much more lack of acceptance of young widowed people than there is for middle age or older widowed people," Feinberg said. "Society expects people to lose their spouses as they age. They don't expect young widowed people and they find it very, very scary."
Wendy Clough in Seattle was widowed in 2006 at age 36. Her husband died suddenly of a seizure as he slept. He was only 37. They had two children and had been trying for a third. She found out she was pregnant a week or two after his funeral.
"It's been a sad, devastating, beautiful journey," said Clough, who falls among just 1.1 per cent of women widowed between the ages of 35 to 39, according to 2009 U.S. Census data.
About a month after his death, Clough tried a bereavement group at a church.
"I walked in and I was the only one who didn't have grey hair. They were totally just as sad as me, but it's just so different. They lived with their spouses for years. For me, I felt very gypped. I didn't get all that I was supposed to get. My kids were also just so gypped," she said.
Managing active careers, the need to earn money and the tender feelings of hurting children are key factors that send younger widows in search of others their age plunged into similar circumstances.
"Your kids are so devastated and they need you so much, and you need time to not be needed for a while. It's hard right away," said Clough, now 44.
Brenda Sieglitz in Pennsylvania's Lancaster County was widowed nearly seven years ago, at 24. She had only been married a year and a half when her husband died of cancer.
"I felt like no one could relate. The only people I knew that were widowed were a step-aunt and my grandmother," she said.
Many close friends remained in her life, offering needed support. Others didn't.
"Some just sort of fell away. They didn't know how to handle me. I was very open and honest with my grief. I wasn't shy about talking about it and I think that might have been difficult for some people who were grieving the loss of him as well," Sieglitz said.
She found help online through Soaring Spirits International, a non-denominational social network created by widowed people for widowed people of all ages and gender orientations. The organization runs workshops tailored to subgroups (loss by suicide, loss with young kids, loss before the chance for kids) at weekend "Camp Widow" programs in San Diego; Tampa, Florida; and Toronto.
Feinberg, who now lives in Raleigh, North Carolina, recalls other issues among the young widows she met and helped back in the 1980s. She sees many benefits to men and women widowed young bypassing traditional circuits and seeking out their own.
"Young people feel comfortable talking about sex. The older people don't. Young people want to get out there and have affairs again. The older people, maybe they do but they don't like to admit it," she said.
And especially for women, Feinberg said, problems can arise in friendships.
"Some young widows have that problem when their married friends are jealous of their single status and won't let them get together with their husbands," she explained. "They walk through the supermarket and everybody turns their carts in the other direction. It's so horrific for them when people can't handle it or only get together without their husbands out of fear."
In these interconnected times, she said: "The best thing for them to do is look for another young widow, however they can."
Follow Leanne Italie on Twitter at http://twitter.com/litalieSuggest a correction