You should reply to someone when they text you.
Travis has car trouble and sends his wife Amanda a text asking her for help while she is chatting with friends in a cafe.
Amanda wants to stay at the cafe.
Amanda tells Travis where she is, and offers to call him a tow truck.
Amanda glances at the text, and then puts her phone in her pocket without responding.
Travis is understanding with Amanda and thanks her for helping.
Travis gets suspicious of what Amanda could be doing and loses trust in her.