So wait, couples are 'forced' to live together? You would think a couple would like each other to some extent, and in a lot of cases enough to gladly live together.
Not everyone is in a relationship. The forcing is due to money - if you're poor enough, then you simply can't afford even a studio and are forced into having roommates to split the cost of rent.
I meant roomates but to be honest, it could be the same for couples. If couples don't wanna live together, why not? Because its not the accepted social behavior? Meh. It's up to the couple, nobody else.
I believe your parent meant having roommates, but even still I think people move in together much earlier in the relationship in expensive cities than they would otherwise.