Originally Posted by Filia
Beside that: If you are in a polyship with some characters, it would be nice if they date others, so that not the Tav is polygamous but the LIs also. Like Halsin want's the Tav to have other lovers but he doesn't want to? Why does he even insist on playing by his rules then?
They just added it for the sake of having the option of Halsin being a side chick to the most popular male and female origin character, because they saw all those thirsty pictures (esp. Astarion x Halsin) on X when people still asked for Halsin and decided that's the way to go. Then they added a lot am ambiguous lines so that players could make up their headcanons with Tav and Halsin living together in a wonderful monogamous relationship while raising the orphans and it worked! Larian went for the cheapest way and it paid off.
In the epilogue, from what I remember, they never said Halsin and Tav are in a relationship, it's just that they arrive together and lived together for 6 months, not more, not less.

Again, I don't mind any polyship, as long as the player (who paid for the game) is the one to decide if so and with whom instead of being forced to a specific combination which might make people feel uncomfortable.
Of course this would need additional investment on Larian's side, but let's face it: This game is only about companions and relationship, like 90% are giving a damn about how bad the main story, the fights, act 3 and w/e are. They don't care about the lore or if the story could even work within DnD rules, they just want more kisses, more hugs and more relationship content, so just throw out a $20 romance DLC and it will be selling like sh*t.
I would've accepted it only if you could do poly with every companion. But lets face it: it's insane amount of work/reworks. So they should just focus on polishing "problematic" sides(like differnt paths acceptans of poly for SH/Astarion, Halsin himself and an option to have fine mono relationship with him, Halsin's "predatory" advances etc.).

Funny, while I see a lot of Halstarion(Halsin+Astarion ship), I don't see a lot of SH+Halsin(it's like her last ship, SH+Karlach and SH+LAezel are the most popular), so idk why they decided to added this for fans. Propbably just writer wanted this.