I mean it's a pretty traditional romance story of you courting her throughout act 1 with the 'first date' vibe cliff scene, confessing your love for each other in act 2 and having a sweet love scene that also helps her get over her past trauma in act 3, followed by wanting to spend the rest of your life together and starting a family when the world is savedTM. While making it more interesting in that neither of you know she even has that trauma because of the forced amnesia and thus she's somewhat distant and secretive at the start, and as things unfold you both come to realize her being under Shar's control isn't good for her. Which makes it fit well with Dark Urge because that story is somewhat similar, so then it doesn't feel like she's the only one going through shit and the support isn't a one-way thing.
None of it screams 'girl that's dtf everything that moves' which she turns into in act 3 and only during these optional scenarios, while remaining true to her writing for the rest of the romance story. But we already know all of that. I disagree that poly or open would work for Lae'zel though. Only act 1 Lae'zel and Astarion fit this bill, but they both change in act 2 as well. And if you read between the lines a little, Karlach throughout the game can fit it somewhat.
