The pair announced their engagement last December.
Five-eighth Blake Green will captain the Warriors against the Eels, and the club has been given an exemption by the NRL to replace Tuivasa-Sheck with versatile seven-game rookie Charnze Nicoll-Klokstad coming into the squad.
The third-ranked Warriors – who are already missing injured halfback Shaun Johnson - will desperately miss the services of the champion No 1, as they look to bounce back from last week's demoralising 32-0 loss to the Sydney Roosters.
Tuivasa-Sheck has been a rock for the side throughout their strong seven-and-three start to the season, making inspirational plays each week on both attack and defence.
But Warriors CEO Cameron George said the club fully supported Tuivasa-Sheck's decision to sit the game out and put family ahead of football.
"His fiancé is expecting," said George.
"They had an appointment with the doctor today.
"He wanted to ensure that he was around to support her obviously if the situation arose and we as a club fully support his decision. Family comes first and football comes second.
"It's important to him and Ashley and we fully endorse his decision and we have 17 other players that can do the job."
Warriors coach Stephen Kearney echoed George's sentiments and said he had no problem with Tuivasa-Sheck's decision.
"We all support Roger and Ashley and wish them all the best," said Kearney.
"It's an incredible time in their lives and we're excited for them. There's no question for us in circumstances like this. Family always come first."
Tuivasa-Sheck's late withdrawal comes after the Warriors were sweating on the fitness of fill-in No 7 Mason Lino, who has been named to start against the Eels despite carrying an ankle sprain suffered last week.
The side also welcomes back hooker Issac Luke after a two-week absence following a shoulder injury suffered in the Anzac Day defeat to Melbourne but will be without Johnson for a second week after he suffered an ankle injury in the round nine win over Wests Tigers.
