Married couple pretend to like each other due to crystal sculpture

Years ago, I remember reading a short story (as I remember it) about a couple whose prized possession is semi-living crystal structure that is sensitive to their relationship; it grows and maintains its beauty as a reflection of how good their relationship is. Because they are so invested in their crystal, they act happy and content while secretly loathing each other… effectively, slaves to the crystal by choice.

I probably have a couple of the details wrong. I believe I read this in the late 90’s or early 00’s.

I’d really like to track this down. It predates Facebook (or social media in general) but feels like a great metaphor for couples that maintain an outwardly happy face.