I am not sure if it helps, but to me her act 2 dialogue when in a love triangle didn't indicate that she was generally opposed to the idea. To me her answer seemed more situational. I dumped her for Astarion and Gale, with the former she was concerned for him and thought getting the player's undivided attention would be good for him, while with Gale she was concerned he'd turn it into a competition and she'd be left at the sidelines. For me this wasn't an objection to the idea or even to the suggested companion, but that it would be a bad idea in the moment with the person involved. So what I got from the conversations was mostly that she cares for her fellow tadfools (as well as herself) and values everyone's well-being more than her personal love life. Just my impression of course.
