Okay not to be blunt but here goes..I am sure not going to condemn someone for engaging in premarital sex, when I have done it myself and if I was in a situation where I was with someone I cared for I would proably do it again under all the right circumstances which does not include marraige...
If a Christian, whether you or someone else, engages in premarital sex but later repents of it, the Bible says he is forgiven. Of course, that's no license to go out and do it again if one remains unmarried.