Remember when you were a teenager and your parents were all suspicious? They wouldn't let you hang out with your boyfriend in your bedroom, even though that meant you never got to have a private conversation, because your little sister kept butting in?
And no matter how much you explained that you weren't DOING anything, they still gave you that look with the one raised eyebrow, and told you, "Fine, but, you can be not DOING anything out here in the den, with your brothers"?
Remember how your younger siblings kept walking up to you and saying stupid crap, and no matter how much you complained about it your parents never stopped them? Like they had NO IDEA how frustrating and annoying and embarrassing that was?
Remember how your boyfriend's parents were a little more lax, but if they saw you making out they would look at you, their son's adoring girlfriend, like you were a complete idiot who didn't have the least instinct for self-preservation? And like you ought to hold out for a guy who at least had his own car?
As it turns out, it wasn't because they didn't understand you. It was because they understood all too well, and had no. interest. in. becoming. grandparents. yet.
So, it all makes sense. The Sons can have privacy with their girlfriends when they are old enough to sign a lease on their own place.