Considering more than 50% of marriages end in divorce, maybe a worthless symbol is fitting.
“See, our love is just like a diamond: Turns to coal under high pressure and to smoke when heated.”
Edited for facts
Diamonds turn to coal under pressure? I thought it was the other way around. i.e. formed from coal under high pressure.
The fact diamonds can burn is pretty crazy, but it makes sense since they’re mostly (entirely?) carbon.
Edit: Sorry for ruining your otherwise perfect analogy :)