Nolim The contrast was meant to be between being single and having a supportive partner, or being being in a relationship where the partner wasn't supportive (which wasn't broken down on the sahp and wohp lines at all). Some people do have partners who aren't supportive- either practically or emotionally.
So a bit more along the lines of what seriouslyiffs suggests, except we don't have an enormous mortgage and he is unlikely to leave his workplace anyway. As he had already gotten his 15 year long service award by the time we met (he's been there since he did his student placement whilst at university) and now he's an equity partner. He is happy there and the place has a really good work culture (it's regularly on those 100 top places to work lists).
He was always on that track anyway, just getting into a relationship that made him happy boosted him a lot. Not least because he cut his hours from about 65-70 hours a week to about 50-55 when he finally had a reason to leave the office other than Sky Sports. Having someone to go home to prompted him to evaluate his work performance and focus on effectiveness not presenteeism and I think that helped him a lot.
And, to be honest, he easily does half the housework, he probably does a good bit more than me to be fair (enough that I sometimes feel guilty). He thinks if I am the one does all the cooking Monday to Friday, that's enough to be my side of the housework. But he does all the cooking at the weekend.
During this time he has also supported me during bad depression due to the death of a parent, when I really couldn't get out of bed most days for months. He took all the practical strain then- cooked, cleaned, held me whilst I alternately cried or stared into the distance.
I think my point is, it can work for some people. It is absolutely correct to be worried about future finances, what happens if you split up/someone dies etc. But there are ways through that other than both people working. It does depend on the actual level of trust you have between the two of you based on experience of one another, and what steps you are able and prepared to put in place to manage some of the other issues. Like a lump sum in the sahp's name, ongoing saving and pension contributions in both names, how household responsibilities will be divided, life and incapacity insurances for both people. There's not a blanket answer to "do you trust one another enough to do this" that is valid for every couple, it really does depend on circumstances.