Eric Ivan Ortiz-Rivera, 36, followed the crowd from a housewarming party to Pulse, according to former roommate Abismael Colon Gomez.
"I am really in shock that he was in the club, because he was not usually a club-scene person," Colon Gomez told the Orlando Sentinel.
Ortiz-Rivera worked in merchandise management and had earned a degree in communications from a university in Puerto Rico.
He left behind his husband of a year, Ivan Dominguez; they were married June 26, the day the U.S. Supreme Court gave same-sex couples the right to marry in all 50 states.
"It was a big and happy coincidence," Dominguez, 30, told The Associated Press. Dominguez is grieving, but said he still feels connected to his husband. He was not at the nightclub because he was supposed to work the next day.
Another friend posted on Ortiz-Rivera's Facebook page after learning of his death: "God just gained one funny and caring angel today."