And as your icon points out, Shawn/Jules means they have to find somewhere to put Gus. And a 3 person marriage probably isn't the way to go for Jules. It'd almost be like acquiring a pair of kids. (Though I generally-based on the first two seasons-interpret it as Shawn is fairly serious about Jules but not nearly mature enough yet, or ready to settle down, while Jules likes him but isn't interested until he finishes growing up.)