Ryan De Nino, who appeared on Lifetime's "Married at First Sight," is dead.

A family member tells TMZ ... Ryan died suddenly earlier this week in New Jersey.

We're told the family is not releasing details about the circumstances surrounding his death at this time.

Ryan was introduced to "Married at First Sight" viewers when he appeared on Season 2 of the Lifetime reality series in 2015.

At the time, he was a 29-year-old businessman who was paired with Jessica Castro ... with the two agreeing to marry after meeting for the first time at the altar.

The couple ultimately decided to stay together on Decision Day, but their relationship later ended in divorce.

His sister Melissa posted a touching tribute after his passing, saying ... "Life as I know it will never be the same."

Ryan was 40.

RIP