This page contains all the information you need on how to begin, and keep, a romance with Thane Krios.
Reunite with Thane
Thane is one of the romances you can do as a Female Shepard if he survived the suicide mission. However, you’ll only be able to continue the romance with Thane in Mass Effect 3 if you were in an active relationship at the end of Mass Effect 2.
Upon completing the mission, Priority: Palaven, check your Private Terminal and you’ll see a message from Thane requesting you to meet him at the Huerta Memorial Hospital which is located at the Citadel. If you had a relationship with Kaiden in Mass Effect 1, Thane will question it and you’ll want to respond with “We were intimate once” in order to continue you romance with Thane.