Is this mattress good for couples?

Yes. It isolates motion well at 8.4 out of 10, measuring about 4.96 m/s2 and settling within roughly a second, because each of the 815 coils is sealed in its own pocket and compresses independently rather than transmitting movement across a connected wire grid. Edge support is also a standout at a perfect 10 out of 10, so the full width stays usable and neither partner rolls toward the middle. A partner shifting at night should not wake you.