Exactly. It's sort of hard to believe that she's a DCF female character. She fixates on Spock from the moment she first sees him on a viewscreen, and from that point forward, almost everything she does revolves around her immediate romantic/sexual fascination with him. That includes willingly committing suicide (she thinks) by grabbing him as he beams out!
And then we have this: What were Kirk and Spock going to do if the commander had been a straight male, or a gay female, or someone not willing to be instantly seduced by an enemy officer? Oof. I'll sort all this out while my turbolift car takes about two minutes to get from the bridge to Deck Two.
It doesn't make any sense for this episode to rely on Spock seducing the Commander. Maybe they made this up on the fly.
For me to make this episode make any sense Starfleet Intelligence would have had to spread the rumour to the Romulan Empire that Spock was unhappy, that he was upset by not being offered a captaincy, that he was sick of being second banana to the often irrational Kirk.
Maybe Romulan Intelligence set the female Romulan Commander out to keep any eye on the Enterprise as it skirted their borders hoping she maybe had a better chance with the seemingly 'disaffected' Spock.
I actually think she was more interested in the Enterprise than Spock and was using him like Bond used the ladies. She probably got a little overinvested personally not being as good in the spy business as our heroes who admittedly weren't that heroic in this episode.