You may have a sleepover with your significant other every night, but when you're under your family's roof, their rules apply. If your parents, grandparents, or other hosts are traditional that probably means sleeping in different bedrooms until you're married.
It's often easier to play along, and miss out on cuddles and pillow talks, than argue with the folks about it. But, you could always try compromise by offering to sleep in separate twin beds in the same room — at least you'll get to vent about the family craziness that inevitably will ensue.
Source: Flickr User lavilleautady