Originally Posted by Rotsen
It's mostly through party banter (Although I have to say that party banter seems broken the more I look at it. Not reading flags properly, not activating at all etc.).

I can't remember the exact words but as soon as you are done with his romance/sex scene he flirts with the person asking/talking about it and asking them to join.

And another thing to add in regards to Halsin. (but it can apply to the rest of the game) Halsin and his flags are entirely broken. I've been reloading saves, trying new playthroughs (romanced/not romanced/romanced someone else) and Halsin thinks my character is in a relationship with them no matter what lol. Romance some other companion and a (!) will pop up above his head as soon as you finished with the sex scene and he will start the poly/sharing conversation even if you rejected/ignored him.
Here's here to take Gale's place now that his fixation is patched out, lmao