Olivia decided to stay at Ethan's side for the time being. One of the reasons she did that was because he had the means to protect her.

The other was that Leia hated her. If she left, Leia would stop coming after her. She wanted to use Ethan to lure Leia out.

She didn't tell Ethan that Colin was Leo yet. The current situation was still unclear. She had to keep an ace up her sleeve.

She was sure that Jeff was safe in Colin's hands. She still needed him to operate on Jeff, so she didn't want