Abortions are not a good answer. At three months, a foetus is fully formed, with a heartbeat and a life which should be considered very carefully. So with marriage. Someone with memories of other sex partners, may be seen as less desirable than someone who is unspoilt. Casual sex takes the trust out of our future marriage Those who cannot control themselves before marriage won't be fully trusted when difficult times come after marriage.
Casual sex can become addictive.
It makes use of the other person. Sex without marriage is sex without commitment. The act of sex usually makes people want security and stability - this is particularly true of girls. If this is not obtained, they can become depressed, and even suicide attempts may follow. Guilt after casual sex can damage people, and any future marriage.