How do I unlock a locked iPhone 6?

So my girlfriend locked her iPhone and I feel like she's texting people behind my back How do I unlock her phone?

Well the purpose of a phone that has the ability to text other people, is to… Well text other people. You don't unlock her phone, you ask her to unlock it, if she says no, the answer is no, and you drop the subject.

She is your girl friend, not your slave, or property. If you want to know what she is doing or who she is texting or calling, you ask. I lock my phone too, and I'm the only one that touches it.

You don't. Her personal conversations are none of your business.

Ou will never be able to unlock the Iphone, its the way they are made, so use a listening device