The notion of staying with a partner for life is one that is far from common today but for most of our ancestors it was the norm. They lived in small communities, so had little choice of partner but they knew them well before they got hitched. I have noticed a number of famous couples who died soon after each other, and my sense is that it was common. The law of coverture meant that the woman became legally invisible when she married, which seems draconian, but they worked together as a single unit. This is from Paupers & Pig Killers:
“I married a couple this day and then moved off to Plainsfield to administer the Sacrament to poor Mrs Morle who is in a very weak way and I fancy going off the Stage after her husband I have observed when man and wife lived together for a long time they always follow each other in a very short time to another world. She was far gone in dropsy and five daughters around her who all received the Sacrament with her. It was indeed a most comfortable sight. One of them was in Service and came to see her mother on her way to Lady Byron her mistress. Another daughter was Mrs Shepherd, married in he neighbourhood.