Some thoughts... So first off, the companions don't have a will of their own, so if they suddenly come up with the "lets shag a bit dialogue options" it is because in some previous dialogue you initiated the romance, intentionally or not.
Which directly leads to the first problem I see. Most of the time you have absolutely no idea what the companions still consider normal dialogue and what they consider sexual interest in themselves. You can guess, but just maybe Larian should mark these options.
Second problem I see is, the approval needed for initiating a romance is way to low. Basically a few friendly words and they want to play all kinds of funny games with my poor little paladin. Virtue be gone.
Third problem, mixing general approval with romance is a bad idea. If you sympathize with your companions, show genuine interest in them, do their quests, be supportive and so on, that should not lead to romance. The game however only knows romance, so even if you are on "we are just good friend" terms with all of them, their story relevant cut scenes and camp dialogues will still be sexually charged. I'd really like to hug my despairing wizard, I hug my real world friends all the time. There is no harm in a little dance, I dance with my female friends literally at every party... In other words, the game lacks nuance.
Last problem, that stuff is genuinely bad designed. The romances and the characters lack depths and complexity. Nobody has any personal preference, camp is downright horny land and everything that sees you in that game, including mind flayers, demons and a horny bear that turns into an oversized druid from time to time, wants to play butt games five minutes after seeing you.
