My wife and I are about to separate, and she somehow seems to know about private text conversations I had with my best friend. I'm almost certain she doesn't know my iPhone passcode or Apple Account password, and I don't leave the phone unattended. Could she have gained access through an old device, message syncing, forwarding, Face ID, or spyware installed in the past? What should I check and change before beginning the divorce process?
4 Answers
Before assuming spyware, consider other access points. Someone might be reading messages from a previously signed-in device, learning information from another person in the conversation, or accessing voicemail if the carrier PIN is still the default. Change passwords everywhere, especially for your Apple Account, email, and mobile carrier, and use unique passwords with two-factor authentication.
Start by checking every device signed in to your Apple Account: Settings > your name, then review the device list and remove anything you don’t recognize or no longer use. An old iPhone, iPad, or Mac with Messages syncing enabled could expose your conversations. Also review your installed apps, sign out of browsers through your account settings, enable two-factor authentication, and change both your Apple Account password and iPhone passcode.
Check Settings > Apps > Messages > Text Message Forwarding and turn off anything you don’t recognize. It’s also worth reviewing Bluetooth connections and removing unfamiliar computers, cars, or accessories. If you use a shared Mac or another Apple device, make sure your messages aren’t syncing there.
Reset Face ID or Touch ID, create a new passcode, and confirm that the Face ID setting requiring attention is enabled. That prevents the phone from unlocking while you’re asleep or not looking at it. Review which features are available from the lock screen as well, and don’t share the new passcode.

I found only my phone, work computer, and an Amazon Fire TV listed, but checking the connected devices was still useful advice.