I agree so much. It feels like a pretty big oversight. At least throw in a scene of the two of them talking in Avernus if you choose that option.
I've noticed the more I think about it, Wyll doesn't have an Act 1 romance cutscene, like at all like the other characters do. Gale gets the magic scene. Shadowheart the cliff scene. Karlach gets the talk by the campfire. Laezel the bdsm. Astarion MULTIPLE scenes. But Wyll doesn't really get a scene flirting with the character until Act 2, when you dance with him.
A cynical part of me wants to believe this is less because it's meant to be a slow burn, because you can hardly flirt with Wyll at all in Act 1 like you can the others. And more a very convenient cover for the fact that they just don't have a lot of content set out for him in that department, and it shows when you go to romance the others.
I wish the developers/writers would spend less time talking about Astarion for the millionth time, and more on Wyll. Especially on his lack of content in general, or the writing decisions they made for him.
