WARNING: The following contains major spoilers for Black Widow, now in theaters and on Disney+ Premier Access.
Black Widow finally tells the fragmented history of Natasha Romanoff (Scarlett Johansson) in full detail. Not only is her time in the Red Room explained, but viewers also get to see the extended family she has from her time as a child spy. The film introduces her adoptive mother, Melina Vostokoff (Rachel Weisz), father Alexei Shostakov (David Harbour) and sister Yelena Belova (Florence Pugh). Because the film ends before the events of Avengers: Infinity War, it begs the question of whether or not Natasha's family survived the Blip.
Black Widow explains the importance of Natasha's vest in Infinity War as being a gift from Yelena. It's a subtle reveal that shows how much she loves her sister and how happy she is to rekindle that relationship. However, at the beginning of Avengers: Endgame, she isn't wearing the vest and she throws herself into her work as an Avenger. At first, it is implied it's because she lost her teammates, but now, the context may be even more grim.
While Natasha regards the Avengers as the one family that took her in because they wanted to, she never fully opens up to them, aside from Clint Barton. Judging by their conversation about family after her death, it doesn't seem like she told anyone about her adoptive family. Therefore, it stands to reason that even if she took the time to search for them, she likely did so without telling the team. As a result, her desperation to find Thanos the first time and sudden dismay upon learning he destroyed the stones make even more sense. To Natasha, this means that any hope of getting her spy family back is truly dashed.
Avengers: Endgame continues to show in subtle ways how seriously Natasha takes the Time Heist mission without explaining. When Tony says he won't help, it's Natasha who tells him they have to take a stand. Additionally, she and Hawkeye are both ready to die because they'd rather give their lives to bring their families back than live in a world without them. The only difference that might push Natasha harder is that Clint still has kids to raise, and she cares for them as well. She also wants to give Yelena and her "parents" a chance to grow from the people they were into the heroes she knows they can be.
Black Widow also gives very brief hints suggesting that they may have been snapped away. For starters, Melina and Alexei aren't seen again after they leave with the other Widows and Dreykov's daughter at the end of Black Widow. Had Natasha known they were alive, she could have immediately called on them and the Widows help her defend the Earth during the Blip. Also, the post-credits scene shows Yelena at Natasha's grave looking remorseful and whistling in hopes that she will whistle back. While it's clear that she was going to be in mourning whether or not she survived the Snap, Yelena cares for her sister's grave in a way that indicates someone who never got to say goodbye. Furthermore, if she were alive after the Blip, Natasha could've immediately brought her to the Avengers compound, where it's safer.
Black Widow fills in many blanks for Natasha Romanoff in between Captain America: Civil War and Avengers: Infinity War. However, the one question that is all but confirmed is Natasha's adoptive family being erased from existence. In hindsight, the answer lies in Natasha's demeanor in Endgame. She is far more desperate to get control of the situation and bring everyone back, and she's more vulnerable than she has been since she was a kid. The theory gains further credence with Yelena's yearning to have her sister back in a way that implies she never got to see her again after she gave her the vest. When all the pieces are put together, it's plausible that Natasha's adoptive family most likely didn't survive the Blip.
Directed by Cate Shortland, Black Widow stars Scarlett Johansson as Natasha Romanoff/Black Widow, Florence Pugh as Yelena Belova, David Harbour as Alexei Shostakov/Red Guardian, O-T Fagbenle as Mason and Rachel Weisz as Melina Vostokoff. The film is now in theaters and on Disney+ Premier Access.