Your worried about your friend but if she doesn't want to stop this then nobody can stop her so the best thing is to make her dua and tell her what she is doing is wrong in a calm way.
i wish indian muslim women wake up & recognise that hindu men have lust for islamic women due to them being banned from marryoing muslim women .Thus, hindu men target them inorder to challenge islamic law & won't leave chance to fornicate with muslim women.
Tell her that One who cannot be grateful & loyal to his Creator will not be loyal to a Human being. Tell these are short illusions and in real life we have seen lovers become enemies later . Tell the verses of Quran http://legacy.quran.com/24/3l