IPhone users read vs delivered?

So I sent a message to my friend and every time she opens my message it would say "Read" but now it only says delivered within the last message I sent her. I know she opened it and saw that message… But how does she make it so that my phone doesn't know she read it?

If you we're to go to setting scroll down to messages and turn off send read receipts the other person wouldn't be able to know when you read their message. That is probably what she has done. Hope this helped. Have a good day!