Does this mattress isolate motion well for couples?

Moderately. Motion isolation scores 8.1/10, the warmest reading among its Beautyrest siblings, because with only a half-inch of foam there is little cushioning to absorb a partner's movement before the 815 coils carry it. Each coil compresses on its own, so it still isolates better than a connected innerspring, and any motion settles within about a second. If undisturbed sleep beside a restless partner is your top priority, a thicker memory-foam build isolates more.