A 30 year old man and a 15 year old child is against the law. It's called rape.
Things are different now days because of pornography, but when my great great grandparents were married, my ggf was 26, and my ggm was 14, and they were married in the Church, and with the blessings of both families. They were married for 60 years (+/-) and had 17 children. She was later a Franciscan tertiary, and all agreed it was a good match.