"May even be on benefits/council housing"
I've a question for the OP; if the person you were in a relationship with was just a "poor" peasant earning below minimum wage and they, I dunno, won the lottery or came into a large amount of inheritence, would that change how much you loved them? And likewise, if they earned a large salary and then lost their job, would you stay with them?
For me, as for lots of posters on this thread, it's about ambition, drive and enjoying your job. I earn not very much but love my job. My OH earns a big salary and is very driven and also loves his job - winwin - but if he developed a passion for something that earned him a lower wage and wanted a career change I would support that 100%. As I think most people with half a brain and heart would.