Hi,
It is just as sinful to date a person other than one’s spouse after a divorce as it was before the divorce. A divorce does not dissolve a marriage. According to the teaching of the Catholic Church, no civil court has that power. IF the marriage is determined to have been null from the beginning by a diocesan marriage tribunal, then and only then is one free to act as one who is not married.
Divorced Catholics are still married unless and until the marriage is found to be null.
Fr. Vincent Serpa, O.P.