zsd: It certainly is halacha. The key issue is whether she had reshus or not, either implied or expressed. In the OPs case, it is clear she had no reshus from him. Not even implied reshus.
She had no Reshus in my example and it puts jewish businesses at risk, they will not ask, DO YOU HAVE YOUR HUSBANDS PERMISSION.
Instead of shopping on 47th St for the necklace, she can go to a store like Jareds or Macys where Beis Din has no power
or instead shopping on 13th Ave for the clothing, she can go to Victorias Secret again where Beis Din is powerless