The revelation that Sentry and X-Men's Rogue had a secret intimate relationship wasn't well-received by Marvel readers; in fact, it is often cited as one of the publisher's worst retcons, but with Sentry having debuted in the Marvel Cinematic Universe, and Rogue expected to him soon enough when the X-franchise is integrated into the MCU, there is always a chance their romance could be redeemed.
Sentry: Fallen Sun #1, written by Paul Jenkins, with art by Tom Raney, revealed the Rogue/Sentry romance in an off-handed, some might say awkward way; as Rogue broke down in tears at Sentry's funeral, Cyclops revealed to Johnny Storm, of the Fantastic Four, that she had been with Sentry, something Scott Summers professed to have just learned himself.
The moment immensely confused Marvel fans, who were caught off guard by such a random revelation of an unexpected pairing, and it can be said that this retcon did more to hurt both characters in the long run than help them.
Rogue And Sentry's Secret Romance Retcon Is Held In Low Regard By Many Marvel Fans
Sentry: Fallen Sun #1; Written By Paul Jenkins; Art By Tom Raney; Ink By Scott Hanna; Color By Val Staples; Lettering By Dan Lanphear
The Sentry: Fallen Sun one-shot takes place after the hero's death in Marvel's Siege crossover event, in which the Dark Avengers led a literal siege of Asgard. While there's a misconception that Iron Man killed Sentry, the battle ends with Robert Reynolds begging to be killed to spare everyone from his villainous alter-ego the Void, with Thor obliging and delivering the fatal blow. Much like how the original Sentry miniseries inserted the brand-new character into the fabric Marvel history, Fallen Sun contains many revelations of Sentry's personal relationships with various Marvel heroes.
[Fallen Sun's] biggest reveal concerns a relationship between Sentry and Rogue, of the X-Men, where it is stated that Sentry was one of the only people Rogue could touch without harming them, leading to a physical relationship.
For instance, readers were told in Fallen Sun that Sentry significantly helped Tony Stark with his alcoholism, making him integral to Iron Man's most famous character arc. Most notable, however, is the issue's biggest reveal concerns a relationship between Sentry and Rogue, of the X-Men, where it is stated that Sentry was one of the only people Rogue could touch without harming them, leading to a physical relationship between the two. However, this immediately felt off to longtime Marvel fans when the issue was released in 2010, and the retcon's reputation has only soured further in the fifteen years since.
X-Men Fans Don't Like How Rogue Was Used To Make Sentry More Important
Fans Dislike How the Twist Elevates Sentry Without Adding To Rogue's Arc
Rogue and Sentry's romance retroactively insert their relationship into Marvel continuity, but moreover, it asserts Sentry as an important presence in Rogue's life. Or, at least, it should in theory. On paper, being with Sentry marks a pivotal point in Rogue's life in more ways than one, and in a way, makes her powers more tragic. Had any of this been seen on-, Sentry could make an argument for being a better love interest for Rogue than Gambit. However, this comic isn't framed to uplift Rogue, but rather to bolster Sentry's legendary status in the minds of readers.

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This is why the revelation feels like a disservice to Rogue, and why so many fans loathe it. The romance reveal uses Rogue as a prop to highlight how special Sentry is as a character. This revelation isn't made to add layers to Rogue's character, nor does it inform readers of something new or refreshing about her journey. Even worse, the sight of Rogue sobbing over a love affair no one knew about as other heroes gossip behind her back isn't a flattering look. The story sacrifices any modicum of respect for Rogue in favor of enhancing Sentry's reputation.
To Be Fair, Sentry's Entire Existence In Marvel Canon Is A Massive Retcon
The Hero Is Retroactive Continuity Embodied
The romance between Sentry and Rogue was retconned into Marvel continuity, but Sentry himself was retconned into the Marvel Universe. It started with his first appearance, establishing Bob Reynolds as a former superhero who everyone in the Marvel Universe forgot about, including himself. When the Void, the evil entity within him, became a problem for both Bob and the people around him, he worked effortlessly with Reed Richards and Doctor Strange to ensure that himself and the rest of Earth-616 forgot who he was, believing that if he didn't being Sentry, then the Void could never manifest again.

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The Sentry has been around for a while now, with his creation needing to follow one specific directive to make him stand out as an all-powerful hero!
The miniseries was always supposed to be self-contained within itself, hence why he's once again forgotten at the end of the story. Even if trying to understand Sentry's place in Marvel history isn't the tidiest and doesn't completely make sense, it wasn't supposed to matter, because Sentry wasn't meant to be a mainstay. The series was a symbolic reflection of the company's different eras throughout the decades; Sentry was never supposed to stick as more than a one-off character. However, Sentry ultimately stuck around, and once he was officially integrated into the Marvel Universe for good, that generated confusion.
Rogue being in love with Sentry is one of the things that creates confusion when trying to understand how Sentry truly fits into the Marvel canon. There are more than a few contradictions and inaccuracies when trying to present Sentry as a character who has always been around. This almost makes Sentry: Fallen Sun ironic, as the very problems that the original 2000 Sentry miniseries was trying to avoid by re-establishing the status quo are on full display in this issue. The difference is that no memories are erased at the end.
Addressing Rogue and Sentry in the MCU Could Fix Marvel's Controversial Off- Romance
The MCU Could Cover What The Comics Only Alluded To
Rogue and Sentry just doesn't sit right with readers because it creates more questions than answers, given their romance was constricted exclusively to just a few pages. The fact that no other stories starring either Sentry or Rogue address this has made matters worse in many readers' eyes in the years since. No one wants to talk about Sentry and Rogue, because fans largely hates the idea of the pairing and its implications, and it has come to be considered one of Marvel's most throwaway retcons.
Thankfully, with Sentry's introduction into the Marvel Cinematic Universe via Thunderbolts* and with the X-Men heavily rumored to be following not far behind, Marvel Studios has a chance to fix Rogue and Sentry. The ire and randomness behind Sentry and Rogue largely stems from the fact that all of their moments happen off-. The MCU, if they choose to adopt this relationship, can show audiences how their love blossoms from the beginning, leaving out any confusion or ambiguity that the couple has in the comics. Marvel could turn the coupling of X-Men's Rogue and Sentry into something viewers unexpectedly love themselves.
Sentry: Fallen Sun #1 is available now from Marvel.