In a way you do get to keep some of the husband or wife's SS, if their payment was higher than yours.
When my FIL died, my MIL's amount in her SS check was increased to be what my FIL's amount was before he died.
It used to be that a widow would receive 3/4 of her husband's benefit. That was back when most women didn't work and didn't have their own SS.
Now, unless things have changed, you can still do that, but you don't get your own benefit if you make that choice.