So... they're comparing Wanda and Pietro's sibling relationship to the romantic relationship of Clint and Natasha? Okay!
Nothing too bad here - just more protectiveness.
And of course, the ever popular:
Yeah, so a lot of these aren't that bad, but still. I haven't even posted a fraction of Pietro's overprotectiveness, or their overly affectionate moments. Ultimates just seems like a natural (if squicky) progression.