Couple Vow is a free app (ad-supported) which can be used between two deeply engaged couple to inform one’s status such as (1) current location, (2) list of SMSs which contains pre-registered keywords, (3) list of calls longer than 3 minutes, to the other. You can also (4) set geolocational regions to let the other know whenever you get in/out of the regions, (5) chat each other via WiFi or 3G/GSM/CDMA internet connection.
To register as a couple, install and launch this app to the android phones you have, and then enter id of each other. Just phone numbers are required to register, and you are ready to know the status of each other at anytime.
This app is utilizing own push service to communicate in real-time, but does NOT send/store personal informations into other places than each other’s phone.