That is the main reason. Other things could wrap around that, like money joined together, or properties joined together.
But the children help old couples to stay together and be happy.
My mom always tells me they’re like roommates, they don’t sleep together, they stopped sleeping together for like 8 years. Responsibilities, they bought a house together, they’re older. I was the reason why they stayed together and she told me that if it wasn’t for me she would’ve been long gone. She tells me she’s happy though.