Getting married at a young age doesn't bother me if you're willing to make the commitment.
What bothers me is people who get married and don't understand the commitment, thus ending the marriage in divorce. Or if someone marries a physically abusive person...or a drug abuser... basically marrying someone who's going to do illegal things.
Also, living together before getting married is a stupid idea. If you lack so much faith, don't get married at all, because otherwise you'll get divorced anyway.