Not that there is anything wrong with this little trope. Its just that its been used a heck of a lot on Doctor Who over the years. Since the 2005 restart, love has saved the day on this many occasions: The Doctor Dances, Fear Her, Last of the Time Lords, Victory of the Daleks, Amys Choice, The Lodger, A Christmas Carol, Night Terrors, Closing Time, The Wedding of River Song, The Doctor, the Widow and the Wardrobe and Hide. So for now, its probably best to avoid using this particular plotline if the episode is to stand out for the fans.