For me, the bed is I share with Fidelio not just a bed. It is our marriage bed, and it is sacred to us as a symbol of the rest and peace we find in each other.
Others have slept there: napping children, lazy dogs, family elders. But we don't bring other lovers into it.
Fidelio built our bed, especially for me, with his own two hands, to be our bed in our home forever. This is part of our cultural heritage. There are many other beds in the world; there are plenty of other beds in our house. But our bed is special and sacred and just for us.
Perhaps your metamour feels similarly.