+1 I wish I had mod points. Your comment is completely applicable to South Africa as well. See my post re Developing Countries.
I assume the girlfriend and fiancée is the same person, otherwise you could get into trouble if you chat to both at once!
I'm a South African and most of my friends and family use WhatsApp. In South Africa, as in many other developing countries, SMS text messages are expensive and WhatsApp is used to save costs. BlackBerries are also (still) popular here - free BBM was a main reason for its popularity. WhatsApp's cross-platform capability (iOS, Android, BB and even Symbian) makes is a very attractive option.
Please see the article below: