Redditors in happy relationships, do you ever think about if/when your relationship will end?

Most relationships don't last for very long, but it's kind of assumed that each partner is "all in" until things start falling apart. Indeed, part of the joy of being with someone is looking forward to your shared futures. At the same time, relationships today are almost inherently transient, especially for the younger demographic. A couple in their 20s can be in love, but the likelihood of this love lasting to their 30s is very small, and increasingly smaller for longer periods of time. I'm wondering if this somewhat sobering thought (fact/statistic/outlook) ever creeps into your minds. I'm not talking specifically about troubled relationships or ones with infidelity, I'm actually more interested in average, healthy couples. Let me know!