Hopefully they will allow subsequent dialogue options for marriage. Frankly, I decided to pursue one of the other dialogue options which seemed more fitting when speaking with Nadia which I thought might lead to the same end point of proposal, but the conversation ended abruptly, before I could back out.
Given that she has been the sole romance option as a Consular, it seems a bit lame to say "Oh well you didn't choose this one dialogue option just right so sorry you're outta luck".
Same. (I think you must also have taken the "We don't need words" option). There's been a couple of "letters" from Nadia since then though, covering her thoughts, with companion gifts attached, and they seem to indicate that she does consider herself to be, at least, engaged.
About the gifts though, it feels really odd... she's at 10k/10k affection, and giving away her gifts to some other companion seems pretty horrible.
Maybe if she were to send a piece of moddable gear that you could continue to wear, maybe a bracer or headband, it would actually be good to get and use her gift.