Having your own space for your shit.
Not having to share a closet. Fuck having 2 dressers in one room.
If i feel like sleeping alone or vise versa one of us doesn't have to sleep on the couch.
I snore hella loud and when it becomes to much for my girl she just gets up and goes to her room or tells me to beat it.
When people come over and get wasted we can offer them a room rather than a shitty couch. When i need to get up early and dont want to be fucked with when my girl gets home super late i don't get woken up by her drunk ass crawling in bed with me, and vise vera.
i could go on forever.