Seoul - If ever in doubt about your guy's commitment to a relationship, ask him if he would commit to an app.A growing number of young couples in Asia are sharing special moments in the privacy of Between, a tight networking app that links only two people.In an age of social media overload where tweets, Instagram and Facebook postings can invite unwanted attention from parents and employers, Between feels like a digital safe haven that blocks outside noise and keeps memories just for two.Created by Seoul-based start-up Value Creators & Company, Between hit five million downloads in two years. About two thirds of the users are in South Korea with their average age in the mid-20s. Between has attracted more than half a million users in Japan and is expanding in Thailand and Singapore. Hundreds of thousands of Chinese and American couples have also joined.Value Creators CEO Park Jaeuk said social media fatigue is the main driver behind Between. As more people join Facebook, Twitter, and chat-based services such as Line and Kakao Talk, Between sees a bigger chance to grow its user numbers.- How it worksYou install Between on your Apple or Android device and provide the mobile number of the person you want to use the app with. Most use the app, which is free, with someone they are romantically involved with, though that's not required. Once the request is accepted, the two can use instant messaging, keep journals, exchange voice messages, post pictures and leave comments. Between also offers a blog-like space where the two users can create photo albums and long notes. Pictures can be tagged to a "Memory Box", which arranges them in a stream of tiles. Reminders for anniversaries, birthdays or any special days such as the day the couple first met can be set in the app's calendar. The content created is private to the two users and the app can be password protected.- Hands onSince I started using Between with my boyfriend, it has become the primary way we chat, save photos, plan vacations and keep to-do lists. We have stopped talking on Kakao Talk or iMessage. While I ceased to post pictures on Facebook, dozens of pictures accumulated on Between. Between feels like keeping a blog between the two of us with an instant messaging feature as an added benefit. I can tell when my boyfriend sends an instant message because Between alerts with a unique beep sound. Even for couples like us who sniff at anything excessively lovey-dovey such as wearing a couple ring, Between's simple design and features have a great appeal.