Most people playing with her romance in mind will never think: "Hmm, Shadowheart must be poly" with everything she does and says outside of interactions with Halsin. Why? Because most people tend to play as monogamous. Besides, even if she were secretly poly it still isn't a good thing at all. I'd 100% like to know if she's into that kind of thing before so I don't get emotionally invested in her and feel stupid later.
At worst poly ppl can have relationship with mono ppl, I see no reason why wouldn't she agree to be mono with Tav, if Tav wishes so. Considering how faithful she stays and cares about Tav. Nothing points at her being poly anyway, it's only Halsin inconsistency(Fling or not).
