If you try to romance both Yennefer and Triss you end up with neither. Most other games make romancing characters impossible if you've already got one locked in, but The Witcher 3 does things a little differently. This will lock Triss in as Geralt's main love interest. At the end of the quest when Triss is boarding the ship and saying goodbye, choose the second option: 'Stay with me'.
When you finish A Matter of Life and Death, you'll receive a secondary quest called 'Now or Never' that you can start by going to see Triss.After she runs off into the maze and falls off the fountain into Geralt's arms, choose the first option: kiss Triss. After the 'Count Reuven's Treasure' quest, Triss will ask Geralt to come to see her, triggering the 'A Matter of Life and Death' quest where you head to a masquerade ball with Triss.Here's what you need to do to choose her as a partner: The second of The Witcher 3's two main romances, you first meet Triss in Novigrad.