Interspecies Romance and Love at First Sight are given a pretty realistic take. Steven is the son of Greg Universe, a human man, and Rose Quartz, a female-lookingsentient crystal with a "body" made of hard light who had already been alive for several thousand years before meeting Greg. Greg met Rose during an unsuccessful rock tour for his one-man band and she was charmed by his earnestness and music, while he was entranced by her beauty. At the start of their relationship, Greg has issues seeing himself as worthy of Rose's attention, while Rose proves him right by caring for him, but less as an equal partner and more in the way a human would show to a trick-performing dog. Pearl confirms she's had several flings with other men, which ended the same way as she refers to Greg as just another of Rose's phases. While Gems can perform a Fusion Dance that connects them into one being in ways a human can never understand, Greg proves he doesn't need it as having a hard, honest talk about how he feels is enough to get her to understand how she was acting and starts her on the path to understanding humans beyond their novelty. Things got much better down the line, but it took a lot of hard work and education on both their parts.
It also deconstructs the idea of otherworldly heroes. The Crystal Gems have sacrificed a lot to protect Earth, and they have had humanity's best interests at heart for thousands of years, but they're also borderline Smug Supers who keep their distance from humans at best, and are Good Is Not Nice types that outright belittle them at worst, while showing very little concern or respect for them or their culture, outside of protecting the planet. In other words, when all is said and done the Crystal Gems are still aliens that have a hard time understanding their charges, although they've been trying harder since their leader fell in love with a human.
Love triangles and unrequited love get thoroughly taken apart. Pearl, the smug, jealous lover who blames Greg for Rose's Death By Child Birth (more or less) in many works would hate him for petty reasons and be a toxic person. Not so, as a former member of a Slave Race, she looked up to Rose with fanatical devotion as the first Gem who ever showed her any kindness. She developed an unhealthy obsession with keeping her safe, sacrificing herself constantly and feeling useless without her who defined her existence. When she's gone, Pearl is forced to redefine who she is as a person while going through many painfully accurate breakdowns motivated by her genuine feelings of love. Meanwhile Greg feels he can't do anything to help, while knowing how Pearl feels and believing things can't change. While they eventually start to mend fences, it takes a long time of Character Development on Pearl's part to find common ground and it's acknowledged several times that her grief will never fully go away. Loved ones cannot be simply forgotten about, and even for the winner of a love triangle, it's still a painful process.
As the series goes on, Steven's All-Loving Hero and Actual Pacifist status gets deconstructed. The show never says that it's wrong for Steven to try to resolve things peacefully but his methods don't always succeed because many threats can't simply be talked down. They work on certain Gems like Peridot (who was only on Earth for a mission, didn't know about the history of the Crystal Gems and the rebellion, and was lied to by Homeworld her entire life), Lapis (who only wished to go home and be free from the Mirror), and even the Cluster (a mindless mass of suffering Crystal Gem personalities who don’t want to destroy the Earth) because they’re able to see his viewpoints and react well to his kindness. However, against other Gems like Bismuth (willing to violently assert her own beliefs), Jasper (a Child Soldier who has personal grudges against his mother for her actions during the rebellion), and Eyeball Ruby (who also hates Rose for her actions during the war and is a Sociopathic Soldier), none of them are willing to agree with Steven and they outright reject and try to kill him when given the chance (even after he tries to save them) so Steven has to fight back in self-defense in order to save himself. Those situations forced him to learn that pacifism won't always mesh well with the morally-complex world that he lives in and sometimes Violence is the Only Option. In “Mindful Education” Steven admits that he blames himself for not being able to do anything to help them and finally breaks down after weeks of holding his guilt and trauma in.
Future, the show's sixth season, basically spends its entire run deconstructing the idea of Steven as a Kid Hero and as a Messianic Archetype. With no villains left to fight, no worlds to save, and all his friends growing up and leaving Beach City, Steven is left with no obvious purpose in life. Every attempt he makes to find some meaning beyond his title as "Savior of the Galaxy" only serves to make things worse, and the sheer trauma of the things he's been through throughout the series kicks in. As his body, mind, and emotions slowly deteriorate, a dark side of his Emotional Powers emerges that the main series only ever briefly touched on.
Pursuing dream jobs is also deconstructed throughout the series. Greg had legitimate reasons to go into music — his family was overly controlling and he wasn't doing well at community college— but he fell prey to an exploitative and incompetent manager named Marty who saw Greg as an asset and didn't even know how to run a merchandise stand. (It was only about fourteen years later that Marty gave Greg a ten-million dollar royalty check for selling one of Greg's songs to a burger brand.) When he quit the tour to pursue a relationship with Rose, his money ran out over a matter of months, and Greg got a Jerkass Realization about mooching off Vidalia after Rose nearly got baby Sour Cream killed. He then takes a stable job at the car wash, which allows him to support his son after Rose dies. It's implied that Sour Cream could easily go the same way as a DJ mixer if not for Yellowtail both telling him to have a fallback while supporting him wholeheartedly. Indeed, after the Time Skip, most of the Cool Kids are seeking practical careers because they're not kids anymore.
Sadie is the exception to this, and it's justified. She spends most of her teenage years working a menial day job, but it was only fun because her friend Lars was there. Her tastes are also inexpensive since she mainly likes investing her wages into horror movies. When Sadie does quit to join the Cool Kids' new band, it's because she's both burned out of working at The Big Donut and has enough savings to justify trying the dream job. Greg also becomes their manager and uses his experience and millions to sponsor their career selflessly. If not for how Greg's career went south, he wouldn't have helped Sadie Killer and the Suspects avoid the same pitfalls.
Free-Range Children also gets deconstructed with Steven. He had a childhood of doing whatever he wanted before going on Gem missions, with minimal structure, because Greg didn't want to repeat his parents' mistakes. Comics revealed that homeschooling gave him a proper education. It means, however, that Steven has never gone to school and he points out that normal college isn't necessarily an option or would be much harder to achieve. In Future, Steven goes Oh, Crap! when Connie reveals she's looking at colleges a few years early and remembers that he never had official schooling, so joining her would be harder. After his breakdown, he decides to spend a year traveling the country, to figure out what he wants to do with his life, and join Connie at her college visits.
"Dewey Wins" deconstructs the Heroic Sacrifice trope by showing the ramifications after Steven returns to Earth after turning himself in to Aquamarine and Topaz to save the others from the Zoo.
Steven just returned from Homeworld due to a move that could have gotten him killed. This episode starts with Greg and the Crystal Gems watching him worryingly from the window as he leaves to take Connie home.
Steven expected some respect for performing a Heroic Sacrifice to save everyone. Instead, he finds out Connie is absolutely furious with what he did and gets a tounge-lashing from her. She deconstructs the concept by pointing out that 1) it was an incredibly risky and foolish move that absolutely terrified everybody because they all thought he was dead, 2) Connie believes Steven's sacrifice proves that he didn't believe or trust that anyone could have helped him with Aquamarine and the Topaz Duo despite the fact that they had taken on worse enemies together and won, and 3) Steven acting like the emotional anguish he put his loved ones through doesn't matter was not okay.
After Sadie learns about Lars' Disney Death and the fact that he's still on Homeworld (albeit with some nice Gems who are also hiding from the Diamonds), she pretty much freaks out and breaks down crying. While Lars might have been able to Came Back Strong, it doesn't change the fact that her coworker, friend, and possible crush died. Lars' parents are also not happy with what happened to their son. It also reinforces that while Lars was an insensitive jerk, there were those who still cared about his well-being and safety.
Mayor Dewey's Head-in-the-Sand Management finally catches up with him after the alien abductions, as it caused most of the town to make him into The Scapegoat since he was their leader and he didn't really do anything about it. This inspires Nanafua to run against him to become mayor herself and fix the problems in Beach City. And Dewey, who has run unopposed his entire life, has no idea what to do when someone is actually running against him.
Steven tries to take the blame when the town blames Mayor Dewey for the alien abductions, so that Dewey will be reelected. He is technically correct that it's his fault, and that the mayor had nothing to do with it since even the Crystal Gems couldn't stop Aquamarine and Topaz from flying off with the victims. No one will hear of it; the Beach City residents know that Steven is a child while Mayor Dewey is an adult with heavier responsibilities, he shouldn't have been put in that position in the first place, that he also gave himself up when no one expected him to do such a thing and were screaming at him not to go with their captors. People like Sadie and Jamie saw that Steven was risking his life while trying to rescue them. The Gems and Greg in the meantime also reveal they understand why Steven made a choice like that, even if they aren't happy with his choice, because it's what Rose would have done and they've unwittingly impressed on him that he needs to live up to her legacy.
Steven finally realizes what Connie meant after going on an almost identical rant with Mayor Dewey. He tries to call her and make amends, but she doesn't respond. Like the "Cry for Help" example in Season 2, serious friendship problems cannot be solved within an 11-minute episode. It's not until "Kevin Party", five episodes later, that they fully reconcile.
"Growing Pains" does this to Steven's Made of Iron trait showing that Steven being subjected to so much trauma and constantly having his life in danger from such a young age has left its mark on his mind and even his body. Now, he can't handle the minor stress from mundane problems without reflexively reacting as if his entire life is in danger, because that is just what he has been experiencing for so long. And those slapstick moments throughout the franchise that could easily amount to Toon Physics? It isn't. Steven actually would have died from everything that happened to him, and the only reason why he didn't is that his Gem half quickly heals him.
