I read your earlier thread, too - but not all of it, as I was getting pretty irritated by the tenor of replies.
Coincidentally, I recently found this: Rent, groceries and household bills cost much more if you're alone, January 2023.
The article's about single "people" and, as others have highlighted, the situation's even worse for women due to lower earnings on average and poorer pension provision.
Text (abridged):
Single people are forced to spend £860 more a month on the cost of living than those in couples.
The cost of rent, groceries and household bills were much higher for single people living alone compared with couples, according to analysis from the broker Hargreaves Lansdown.
On average, a single person spends £1,851 per month on typical bills, but someone in a couple would spend just £991 on the same services, the broker said.
Single people were also less likely to have sufficient emergency savings, at 53pc compared with 79pc of those in relationships, a poll by Hargreaves Lansdown found. They were less likely to have enough cash left over at the end of the month to be considered financially resilient.
Sarah Coles, of Hargreaves Lansdown, said: “Single people have less in savings, and less cash left over at the end of the month. They pay the price over the long term too, because they’re less likely to be building equity in a property or saving enough to be on track for a moderate retirement income.”
“Even the tax system seems stacked against you,” she added. “There are specific tax breaks for people who are married or in civil partnerships, from the marriage allowance to the fact there is no inheritance tax on assets passed between spouses after death, or capital gains tax on assets passed while you’re alive."