Yes, but she doesn't recognize the severity. She may associate sex more with love than with sin.
Hello again MsMediator, if your friend doesn't recognize the severity because she associates extra-marital sex with love more than sin, there is a wonderful Book that you can use to help her come to a better understanding of what the truth really is .. if she is truly a believer, that is
If she's not, then what the Bible has to say to her concerning her sinful behavior will not have much of an impact on her unfortunately, which the Apostle Paul carefully explains to us in v14 of the following short passage .. 1 Corinthians 2:12-16, where he contrasts those who are "spiritual" (believers/in Christ) with those who are still "natural" men/women (unbelievers/without Christ).
If you determine that she is CINO/not a true believer, then how you approach her/what you say to her will have to be completely different (of course) since the Gospel will be the focus if that's the case. Perhaps this would be a good time for you to find out 'what' she truly believes about God, salvation, the faith, etc., and 'why'. I have known those who I firmly believed were Christians, but who were not acting or believing as they should, mostly out of ignorance (though PTL, they do now
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).
Still praying for her, and for you too (for the talks that you two will hopefully have)!
God bless you!!
~Deuteronomy (David)
p.s. - one of the principal ways that we are able to recognize when a person who claims to be a Christian is CINO (Christian In Name Only) rather than a true believer is by their lifestyle choices, which are 1. sinful and 2. impenitent, as A. W. Pink tells us.