Complex sentence: Since 5 June 2010, the state became the eighth in the world to recognize same-sex marriage, even though any couple of the same sex are not able to jointly adopt--but they may adopt as individuals.
Split into simpler sentences: Since 5 June 2010, the state became the eighth in the world to recognize same-sex marriage. Couples of the same sex are not able to jointly adopt--but they may adopt as individuals.