I knew a couple who did this-both gay men.
It went from that to open relationship. At which point, with hindsight, the partner who had had to be persuaded said “Well that was obviously a sign it wasn’t working wasn’t it?” They stopped having sex with one another completely at that point.
The one who had to be persuaded then met someone, it got serious and they got married.
The persuader slept around a lot, contracted HIV and suddenly realised a committed, stable relationship was actually what he wanted after all.
But his former partner was now remarried, so he found someone else. The original couple stayed friends.
Fast forward 4 or 5 years...the marriage is on the rocks and ends in divorce (due to infidelity on one side- the one who had to be persuaded was faithful, the new husband wasn’t).
The persuader ditches his live-in boyfriend to try to get back together with the one who had to be persuaded.
The one who had to be persuaded is happy to have an emotional and financial partnership, but not a sexual one. They buy a house together.
The one who had to be persuaded now has a series of reasonably stable monogamous romantic/sexual relationships lasting 6-18 months, at which point the relationship either fizzles out or the new partner realises they want more from a partnership than is on offer, and either (understandably) strops off or makes a serious play to become the main partner, fails and then strops off. Lots of emotional tears, high drama and heartache all round. Lots of friends going “oh god, this again?”
The persuader had lots of no string attached sex at first (sex on no more than three occasions with the same person so no feelings get involved for him), but then got really focussed on his career and took a job involving extensive spells abroad. This is in order that the other partner can have their current flame to stay/live in the shared house without it being too awkward. But when he is back in the UK all three hang out and go to social events as a thrupple, just one he is not sexually involved in. Similarly, as the country where he works most of the year is an attractive tourist spot, the one who had to be persuaded and his revolving regular squeeze take holidays there multiple times a year. He’s not that bothered about sex now, he might have a one night stand when he goes to New York in holiday a couple of times a year, but often he doesn’t.
The persuader is quite open about the fact that what he sees as the main benefit for him (as well as emotional support and friendship) is a nurse/companion when his HIV progresses. He works in a medical field so is quite clear about his life expectancy on medication, % success rates for medication etc. In return, the one who had to be persuaded can expect substantial subsidization during his lifetime (there is a big earning disparity), to receive all his life insurance/pensions/money when he dies and a life interest in his share of the house (proceeds of which will pass to two sisters when the one who had to be persuaded dies).
I find this quite abstractly interesting in terms of “you never know what will work for people” kind of way but found it very emotionally draining to get to know then see discarded the people who came and went through the revolving door. I only really ever see my friend (the one who had to be persuaded) on a one to one basis for drinks or dinner now to catch up, whereas I used to be one of the same social group and see everyone every weekend. It’s pretty clear to me though from some of things he says, that if London houses prices were different, and he could afford to buy on his own, he would do so in a shot and look for another husband.