having sex before marriage is not good, becouse god created each of us in order to share with our future wife or husband ,wonderful details, that is spoiled when we make sins against our bodies, sex is fantastic if you have it inside marriage
One example is when you have something new that was protected and cared only for you,than something that has cuts and is dirty, which of them will you appreciate more?, i don't mean that if you had sex before marriage, you would be a lost case,because god cleans us every day and forgives us when we repent of our sins
the only difference is the great blessings that we lose,when we do your own will,without obedience to god