I don’t believe that’s accurate, either. One, from a practical point of view (homes were so small they’d need to save on space… and “beds” were not something to just have a few lying around! Doubtless they’d sleep together for a lot of practical reasons) and two, from evidence in writing.
That is, Chaucer’s Canterbury Tales clearly depicts couples sleeping in the same bed and having sex in the middle of the night, something I’ve heard elsewhere to be the normal way of operating.
(As an interesting side note, Chaucer also references the world as round. Though it was known that the world is round from the times of the ancient Greeks, this little insight proves in accessible, English writing that people knew the world was round before the time of Columbus. Chaucer was writing at the close of the 14th century)