26-year-old Micah Downey died suddenly Saturday -- it appears he died in the U.S. The cause of death has not been revealed.

Micah was engaged to Milly Johnson. The premise of the show is following couples planning on tying the knot when their families disapprove.

As for Micah and Milly, she's pregnant with their second child but said back in November they had broken up. There were reports -- unconfirmed -- that the relationship fell apart because of his alleged drug addiction.

Milly posted, "It is so sad & unbelievably surreal that i am making this post ... I am struggling to put into words how sad & heartbreaking this is. I just hope he is at peace wherever he is & that he will always be watching over his babies."

She ended by writing, "A bad, bad dream ... I can't believe you're not here. Rest in Peace, Micah."