To bo honest, I don't know why no one has thought of this before. Travelling long distance is something very common in the modern world we live in today, but sometimes we can't take everyone with us. Pair is an app which wishes to aid the pain of long distance relationships. It's mainly targeted at couples, but I can't see why I couldn't work with other people you love, such as friends and family.
Most couples in long distance relationships I'm sure use a number of services to keep in touch, such as SMS, Skype, email, Facebook..etc. Pair puts all of this into one app and only between two people so it's super private and intimate. With Pair you can share all sorts of information such as, messages, photos, videos, locations and even little doodles if you like drawing. The location feature I feel like is a great addition because you can then know if the other person has got home safely.
All of the information you share is put it into one stream, which is made to look like a conversation, with you on the left, and the other on the right. If you're a forgetful one, it'll even show information such as anniversary and birthdays.
A feature which is definitely aimed at couples is the ThumbKiss. When you're both on your phones, you can both put your thumbs on the screen and then both phones will vibrate - creating the kind of reassurance that both of you are thinking about each other at the same time.
The app is only available for iPhone at the moment, but they're working on Android version at the time of this writing and are working as hard as possible to get it out ASAP.