I live with my girlfriend in a campercan with a living space of 5,6 square meter (602 square feet). If one of us needs some space one of us wil just leave the van and give the other space.

Definitely not for everyone though (we can do our own thing in each others presence and we don't need much privacy from eachother). We did need to get used to it at first, but it al worked out.

I guess my point is that living in a single room with eachother is doable for atleast some people.