The This Is Us season finale came and went — and viewers are fuming that Jack Pearson's death remained a mystery.

Fans were quick to share their disappointment on social media following the final episode of the hit family drama, which was not as "heartbreaking" as expected.

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"What a disappointing finale. Totally didn't deliver what was promised," one fan tweeted before another jokingly added, "10 years from now April the Giraffe will still be pregnant and we still won't know how Jack died #ThisIsUs."

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I stand in awe of this friend of mine. He is the ultimate partner in crime and he absolutely knocked it out of the park on every level in last night's finale. I am the luckiest. Can't believe we have 18 behind us and atleast 36 ahead, Mi. Wow. And for those somehow frustrated with the finale not revealing how Jack passed, I would encourage patience. Otherwise you might be watching the wrong show. Last night was fundamental to the bigger picture. The story deviated and ultimately landed on (I think) a more compelling question… what was the state of this relationship in the end? And as Milo so eloquently stated, let's focus on how the man lived! Stay tuned cause it's all leading somewhere and we're just getting started.

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However, while viewers did not get the tear-jerker ending they wanted, Mandy Moore, who plays Rebecca on the NBC series, defended the episode and her co-star Milo Ventimiglia.

"I stand in awe of this friend of mine. He is the ultimate partner in crime and he absolutely knocked it out of the park on every level in last night's finale," she wrote. "I am the luckiest. Can't believe we have 18 behind us and at least 36 ahead, Mi. Wow.

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She continued, "And for those somehow frustrated with the finale not revealing how Jack passed, I would encourage patience. Otherwise, you might be watching the wrong show. Last night was fundamental to the bigger picture. The story deviated and ultimately landed on (I think) a more compelling question… what was the state of this relationship in the end? And as Milo so eloquently stated, let's focus on how the man lived! Stay tuned cause it's all leading somewhere and we're just getting started."

So maybe we didn't see how Jack died, but it did give fans more to look forward to, including Kate's singing career and Randall adopting a baby.

Season 2 of This Is Us premieres on Sept. 19 on NBC. For a look at the cast then and now, click through the gallery below!