people who are not catholic (and never have been) can and do enter marriages that are licit and valid, and binding for life in the eyes of the catholic church, provided that there is no obstacle (such as a previous marriage) to the union. non-catholics who are not baptized do not receive a sacrament (since no sacraments are valid except for the baptized) but enter a solemn, sacred and binding marriage contract between a man, a woman and god. baptized non-catholics possibly receive a sacrament, but since most protestant religions do not recognize marriage as a sacrament, but only a "holy ordinance" or something like that, it would be doubtful if a non-catholic who did not recognize matrimony as a sacrament would actually then receive a sacrament. in any event, for such people marriage is at least a solemn, lifelong, binding and sacred contract.
what this means is that strict christians - catholics in this case - would probably say the marriage is not valid in accordance with their church rules, but would reognise the union in law. i suppose it would be up to the wedded couple as to whether they gave a poop about that.