And there was no "taking advantage" of amnesia or anything. Triss didn't rape or cast a spell on Geralt. She conveyed her feelings. Depending on how you played the game you reciprocated or not. Untold times every single day someone on this planet is wooing someone else that is in a relationship. And just because you know or classify that other person as a friend also has no bearing on it..
No taking advantage of amnesia? Seriously? Triss admitted herself that she was taking advantage of him.