I completely agree with you. I am completing 30 years in in this weekend and in same situation like you. The world is tempting and it will keep tempting you and me for many such things through friends, colleagus. I always thought sex after marriage and never crossed that limit. For me the reason is simple, respecting Gods and his regulations. Can't imagine to be unholy and sit in prayer and raise my hands to heaven after doing pre marital or extra marital affair.
Don't worry, I am hearing these words like old fashioned, I am mad, don't know how to enjoy life, rude at females etc.. for long time. keep it up. God will reward you for this one day.
