It will depend on the person and the circs, but I do think 'love lies' can sometimes be the kindest way.
E.g. my FiL suddenly started asking where MiL (dead 10 years) was. We began by very gently explaining that she had died, but he would be terribly upset and cry, only to forget and ask again shortly afterwards.
So we started saying she had just gone to the shops or to see Auntie So and So. This would keep him quite happy, and because his short term memory was almost non existent by then, he never remembered that we'd said much the same before.
By contrast my mother, who was devastated when my father died after over 45 years of a happy marriage, seemed by a certain stage to have forgotten him altogether. Occasionally, if I showed her a photo, she would say very vaguely, 'Oh, yes, did he die?' and would not be at all upset when I said gently that yes, I was afraid he had.