Romance, love and sex are all part of the human experience, so of course they are part of our fantasy stories as well. By leaving them out, you'd leave out an important narrative element in a story. That's not to say it can't be done, and done well (Lord of the Rings is one of the greatest fantasy stories ever written, and it's centered on friendship not romance, its romantic subplots are off on the sidelines). But I for one enjoy the romantic element in RPGs like this, because when you're in an extraordinary situation with extraordinary characters, it's only natural your character may be attracted to one of the people you're adventuring with, and it's natural for a story to want to explore that aspect. It makes me feel more involved in the story.
Put in the time to do it right or don't do it at all. Don't just put in a bad scene so that you can advertise romanceable companions.
Why is it a bad scene? We only have the companion conversations at the moment, not even any of the companion sex scenes.
For me, the party fling makes sense story-wise. These people have been implanted with an alien tadpole against their will, have been through hell and back (literally), have been thrown together into an extraordinary situation, and haven't had a moment's rest from all the fighting. Finally, something goes right for them, they save a bunch of people, and get to unwind and forget their problems just for a night in a nice atmosphere. Well OF COURSE some of them are horny. :P Sex is, after all, a natural human behaviour, the party is a good excuse to explore that as part of the story, and each of the companions' scenes reveals something about them as well.