Q. 1. Is dating a sin?
A. 1. Dating in itself is not a sin. How else is someone to marry if they do not date?
Dating is a sin when one's intent to date is against the virtue of chastity. If one dates with the intent of becoming involved in a sexual relationship, with or without consent, such dating is sinful.
Your intention is what determines if dating is sinful or not. If your heart is impure, it is sinful.