@Redfuchs the Frau once saw someone get asked "you've been married for X years! What's the secret to making it last?"
And the answer that person gave was that them and their partner never wanted to divorce both at the same time
That's kind of cheekily self evident but it stuck with us due to its simple rawness. A relationship is a life you build together and those are made of everyday victories and struggles. There's no magic, there's mutua lovel care and work. It's being accomplices in life