Aileen pushed forward, trying to corner Zia and make her understand that she already knew something that Zia had been trying to cover up.
However, Zia still couldn't realize her intentions, because what was in her head right now was annoyance that Aileen had been so insolent to her and so dared to fight her openly like this.
She still looked confused in response to Aileen's drastic change in attitude, but even so, the way Aileen was cornering her made Zia feel uncomfortable and she instinctively pushed her away.
Luckily, the push was not so strong that Aileen couldn't get an excuse to fall, jeopardize her 'pregnancy' which could put Zia in trouble.
In this case, Aileen still needed herself to be pregnant in order to tie knot with Theodore, or else she would be dumped right there and then. Therefore, Aileen couldn't use that trick now.
