Complex sentence: He recounts that, in keeping with local customs and community wishes, he was betrothed to his future wife when she was still a child, and later consummated the marriage when she was aged about 15 or 16.
Split into simpler sentences: He recounts that, in keeping with local customs and community wishes, he was betrothed to his future wife when she was still a child. They consummated the marriage when she was aged about 15 or 16.