Possible Clues:

• Texter's sign-off
• "bye 4 now"
• Texting farewell
• 'bye 4 now'
• Texter's 'ciao'
• Texter's signoff
• "going afk"
• "Until next time," in texts
• Texter's "Bye for now!"
• 'Until next time,' in a text