Here is a list of 20 other countries where same-sex marriage is legal nationwide and the year it was approved (Mexico and the United States are not included, since they only allow same-sex marriage in certain jurisdictions):The Netherlands (2000).Belgium (2003).n light of Ireland voting to legalize same-sex marriage, here is a list of other countries where same-sex couples can marry. Ireland just became the first country to legalize same-sex marriage by a national vote—rather than through legislation or the courts.