ideally they'd be a couple of some sort (dating, engaged, married--whatever's clever) that got together in large part to appease the folks back home. they'd carry on a very aesthetic and charming public image and, for all intents and purposes, they do get along quite well. but they have a very open relationship (to the point where they wouldn't even consider their own relationship much more than a convenient friendship) which can get messy. they end up with someone who wants more and tries to cause problems, or they accidentally post to insta/twitter/whatever with too much information, accidentally say the wrong name to the parents, etc.