Romanceable by: Smuggler male characters (possibly female?)
How to start single-planet romance: On Tatooine, the Smuggler will speak with the Sith Vaverone Zare, while trying to get a meeting with Diago. In return for help, Vaverone will offer the pleasure of her company. While there aren’t [FLIRT] options as you complete the missions, you can accept her offer and help her. Amusingly, you can [FLIRT] with the Jedi who shows up, and [FLIRT] with Risha, who shows up on holocall. After a fight, then you can [FLIRT] with Vavarone to claim your “compensation” and the second [FLIRT] option will lead to some private time together and a swim in the cave’s pools. Afterwards, Vaverone concludes her business and leaves, and the romance can not be continued. (Fun fact, you get a mail later after collaborating with her and she becomes Darth Allures.)
*** I found some rumours that it is possible to do this romance scene with a female smuggler character but I could not find any video proof.
How to continue romance: None.