I m explain you about how to see your message histroy on your phone or pc . what is your favourite messenger like facebook messenger or any ohter but however i would like to suggest you if you delete your messenger history you wil be 100% safe . dont leak your message to other people . Although you probably shouldn't be snooping the only way to check it is if you log on as her. If you know her email and pw then you can go in and check her messages which is the obvious solution. Another thing you can do is if you know her email info you can always log into her email acct and not facebook. Facebook send notifications via email when you have something new. If you really do think it's something then you should just come straight out and ask her. You don't have to be confrontational about it just bring it up randomly and in a joking way. you never know it could be something her and her gf's were joking about that may be embarassing to her and she didn't want you to see.
to delete them so they stop coming back, you need to go to the regular facebook website, go to messages, and delete them there. facebook integrated messaging and chat, so anything sent in one will show up in the other, and is saved forever unless you go into Messages and delete the message thread.
1. Go to General Account Settings.
2. Click 'Download a copy of your Facebook data.
3. Click 'Start my Archive'
4. Usually, it take 24 hours for Facebook to collect all your data. Since your messages are very long, it may take longer.
5. After 24 hrs, check again. If the archive is ready for download, type in your password and download the archive to your computer.
Hope that this method works. Good luck!
