It doesn't need to know the sexuality of the player.
It just needs to be more clear about what dialogue options are alluding to.
There's a vast difference between a bro just showing you how cool magic is and him whispering sweet nothings into your ear as you think about kissing him.
Yet the dialogue option with Gale doesn't really make it clear.
It's just "Hey do you wanna see some cool magic?" and then it's suddenly all intimate.
More clarity with dialogue options (And more fleshed out alternate states of platonic and romantic relationships) means you can more accurately move forward in your intended way, without accidentally ploughing into the romance option unawares.
This is a relevant point in general, but the example of Gale is not a good reflection of the issue. When it comes to Gale you do have very clear dialogue options, two of the options allude to thinking about kissing and holding hands and the others are either platonic or downright rude. It does not jump into anything intimate unless you choose one of the obvious romantic options, so you can't really complain that Gale responds with romantic interest when you have been showing him thoughts about being intimate with him.
If you want to highlight the issue then Karlach -"I want to ride you until you see stars"- or Laezel -"I want to taste your sweat"- are far clearer examples since they will jump at you with those lines no matter what you have said to them before. Gale has one of the most clearly signalled platonic or romantic paths out of all the companions, yet he gets thrown around as the example of the person who can't read the room while Lae'zel and Karlach (and Minthara) somehow gets a free pass.
Disclaimer: If you only played the early release of the game, Gale's romance flags were bugged, causing him to act as if you were in a romantic relationship even if you had turned him down or never initiated anything romantic. This was cleared up in the patches, so the issue no longer exists. Obviously Larian should take care that such bugs do not happen when it comes to romance as it is clearly not intended to play out that way.
