My Niece is 19 she has no common sense..advice would be helpful?

As for me, when I was 19, I basically was on my own because i had become responsible, if one tends to keep making excuses for one adults actions, honestly, that is not right. an adult is an adult. sure basically we are in LUST NOT LOVE!!! LIVE AND LEARN..... LIFE IS WHAT YOU MAKE IT, DO NOT BLAME ANYONE EXCEPT YOURSELF,NOT BLAME OTHERS.....