If your daughter’s fiance is not baptized, he is not considered to be a Christian by the Catholic Church. The Church does not offer a nuptial Mass when one party is not baptized because baptism is the gateway to the rest of the sacraments. If your daughter’s fiance is not baptized by the time of the wedding and they marry in a Catholic ritual, they will have to have a nuptial liturgy outside of Mass. Catholics and non-Catholic Christians who marry in a Catholic ritual are usually counseled to have a nuptial liturgy outside of Mass to avoid the problem that the non-Catholic partner will not be able to receive Communion at the wedding.
However, if it is important to your daughter and her fiance to have a nuptial Mass, then suggest to him that he seek baptism in his church. Once validly baptized, he and your daughter will be permitted to have a Catholic nuptial Mass.
