Mic drop. No really.
Imagine you're Therese. It's 1952, you look like Rooney Mara, you're wearing a Santa hat, you're hawking a pile of terrifying looking but also freakishly gender-normative dolls, there's a sign behind you that says "Mommy's Baby," and you've got the span of one sale to signal your romantic viability to customer and apparent goddess Carol.
What's your move? Coquettishly mention that her daughter's chosen doll, Bright Betsy, has a capacity for secretion? No? And that's why Cate Blanchett's not your girlfriend.