Just unlink and talk to her alone.
Alas, whenever you don't want to play RPS, i'd recommend you keep the other character away.
I'd also recommend to have a charisma set of equipment so you can win against yourself the easier way.
The point that Larian missed is that it's fun to have a second person participating in all important decisions. But it's rather annoying when you're playing alone. And if the game has a single-player option, it should have taken that into account.
I found the mechanic of RPS pretty nice. You can even abuse it to win a lot, provided you have at least 3-4 dots for every win. The computer never uses the same thing as you (in 3 simultaneous playthroughs I have never come into a draw with the computer controlling the other character's choices).
