Frank Winterstein has been released from his one-year contract with the Bulls by mutual consent.
The 27-year-old back-rower agreed to join the club in October of last year and went on to represent Samoa during the 2013 World Cup.
But the former Widnes man returned home to Australia to get married last month and is now expected to join a rugby union side Down Under.
Bulls coach Francis Cummins said: “I am disappointed to lose anyone but when I met Frank he did talk about an opportunity for him to play rugby union in Australia.
“He was keen to play out one year with us here in Super League until he got back home.
“He and his wife have just got married and I guess, for a player who has in the past witnessed financial difficulties at other clubs, the uncertainty wasn't great for him.
“If an opportunity has arisen elsewhere for him then we cannot really stand in his way, given the fact we are attempting to make cuts to our playing budget.
“It is an unfortunate situation but I believe we have adequate cover at second-row. He certainly added to our strength in depth but there are four or five guys ready to fill that gap.”