That was because the moment the Earth's Core Avatar experienced her second climax, it was the moment that she lost control of her body, and soul temporarily.
It was like a heavenly release, a moment of weakness that made everything that was real and ethereal experience of full pause.
That was all Eric needed in order to make sure that the Earth's Core Avatar didn't escape his claws, as he immediately sent a Slave Seal on its main Soul Avatar.
While the Earth's Core Avatar was occupying the body of a woman, the truth was that its form was still that of a small blue marble ball.
It seemed like one would need to be extremely strong and ferocious in order to break that blue marble ball and plant a Slave Seal in there, but only if it was 'aware'.