I haven’t watched the episode yet but from what I understand, the CS theme plays during that broken heart exchange. And if the CS theme is playing, then the scene is meant to be seen as romantic. Now, if Hook’s evil villain theme were played, that would be an entirely different music cue.
Musical cues on this show mean a lot. Looking all the way back to the 3A premiere, when Hook and Emma shared a drink on the Jolly Roger toasting Neal. As much as it was a CS scene, it wouldn’t have been right to play their theme then. It also wouldn’t been right to play ST theme either because the focus of the scene is Emma.
So instead of running the CS or ST music in the background, Isham opted for a variation of The Road to True Love from the first volume of the soundtrack. Emma’s theme, which is often sad, generally only plays when she is isolated or feels sad (the pilot, Ariel).
Wine always makes everything better, doesn’t it? Lol.