So...this fits perfectly with my cosmic horror romance vibes. And being an utter deviant for horror, yes -- my protagonists would let the Earth take an L.
While Our Universe doesn't have that big of a stake (though it is a similar worry), Brenda is married to someone on another plane. And that love is so deep that "even if the world crumbled around us, I would still love her".
So while she wouldn't destroy a world for her love, she wouldn't be completely terrified about crumbling along with it. Considering what she's already seen, she'd accepted it.
Tone and genre, my friends