Love is the greatest commandment in the Bible.
Sometimes I would donate to a charity they supported instead of flowers. Or carry on something they started in life...eg my friend was training to be a school teacher. I thought of her as I studied, and volunteer for helping in schools.
On her birthday I do some of the things she enjoyed doing when she was alive on earth. I miss her, but know we will meet again. She tragically went missing.
I know many widows visit their loved ones graves. Sometimes they talk about their spouses to me, they must miss them a lot. Like a song theyd hear and it reminds them of their loved one. I think they get lonely. The believing ones know they are at rest with Jesus though. When they pass on they know their bodies going to be buried next to their spouse.