Me and my gf is 20year old and we are good in studies.we want to have sex before marriage...is it good or not???what do u want to say to me????

This is your life and at least this decision need to be taken by you only.
It never depends on 21st century. Value remains same at all time, what it was in Ramayana days and will remain same in 30th century.

Do what you think best for you. Only you should not repent after few days.