Brittany has heard that the Android phones are having battery life issues. Leo says that the iPhone 7 Plus is one of the best phones for battery life. Apple is also very aggressive about controlling apps on the phone to prevent them from running in the background. The Android phone that Brittany's boyfriend has probably has an ill behaved app that's sucking the battery power out of it. Facebook, for instance, is a battery hog.
Brittany can check in her phone settings to see what apps are using battery life. She can do this on the iPhone as well. A bad cell signal could also be a culprit as the phone is constantly searching for a better signal. Brittany's boyfriend's phone is not going to get anywhere near the battery life of the iPhone 7, though.