For my Commando, I walked a vary careful path of always selecting the supportive but professional answer for Elara. She is now at max affection, and I don't recall getting into a situation where I had to do a flat, cold turn down of any romantic suggestions with her.
On my Shadow, with Nadia. one of the conversations seemed to be leading down a "romance" path, but the question she asked was not particularly overt. The answer I chose was something to the effect of "That is not appropriate" for a master and student. It seemed to be a bit too soon considering she had not really said anything that suggestive yet, but it was the honorable answer without being cold and rejecting her as undesirable in another circumstance. However, it did seem to shut down any additional romance related dialogs from then on.
But I agree with you in general. There seems to be a point where you get locked into a direction you don't want to go and there is nothing you can do about it. This is even true of some of the non-companion dialogs. I am happily married, and I am not interested in pursuing any pretend romances in any game. I am especially not interested in any one-night stands, cyber or otherwise. Yet with Jaxo, in the quest you get to meet her at her apartment, I got put in just such a situation. And when the dialog just started suggesting a romance, I was given a choice that would obviously pursue the suggestion and another that would turn her down rather coldly. I neither wanted to pursue a romance nor did I want to be mean about rejecting her, so I chose what I hoped would be a more neutral option that would either suggest I was not taking the "hint," or would open a less cold rejection. But, no. When I took the more neutral option, I ended up getting a 50s style fade-to-black and a one-night stand I did not want. The same thing happened with the girl on the Hutt barge in the Smuggler's story: obvious pursuit of the relationship, cold rejection, or a more neutral option that ends up in a one-night stand anyway.
It seems like they are assuming everyone wants to pursue a romance or one night stand and that, if you don't, you would naturally just be cruel and cold in turning it down. That is not good for role playing.
you know what is maddening is the way you're railroaded by BW into these situations even against yor chosen responses (or not given the option) while they completely exclude female to female romance. It reeks of a developer dictating what can or cannot constitute a proper romance. If they can force an unwanted romance on us because they assume that's what we want, then they should be able to easily allow a female/female or heck, even male/male relationship.
My female toons are sick of getting hit on by the guys on my ship. Even on my bounty hunter, i get these creepy come-ons from out of nowhere from guys who have like 10 affection when my female companion is maxed out affection (with not even a flirt option).
Check out this completely unwanted dialogue:
Torian: You know... I've been watching you in action for a while now. And what a nice sight it is.
what... the... f....