WARNING: The following contains spoilers for the "Super Sons of Tomorrow" crossover event between Superman, Super Sons and Teen Titans.
Since his arrival in the main DC Universe, Superboy has exhibited an innate charm that makes him hard to dislike. Whether it's his Smallville classmates or humans from an alternate Earth, Jon Kent can win over just about anyone who isn't trying to kill him, whether he wants to or not. In Super Sons #12, for the first time in his short career, Jon's likability ends up not working in his favor.
When Robin's Teen Titans first met the young Kryptonian several months back, they instantly took a liking to him and wanted him to be a part of their team, despite the fact that he's still only a pre-teen. At the end of their fight against the villainous Kraklow, they extended him an offer to fight alongside them at any time, much to Robin's dismay.
As Super Sons of Tomorrow begins, we learn that Superboy was promised by Robin that he would be allowed to join the Titans on one mission once a month. Not only is this a promise Damian has been shirking on for the last three months, the Titans had no idea it was ever made in the first place. But any further arguing on the matter is moot, because the Tim Drake from an alternate future shows up with aims to kill Superboy before he can grow up and unleash his Solar Flare power that'll kill millions.
Having been aware of Drake's existence for some time now, Robin elects to hide Superboy from the man who is calling himself the Savior. Raven and Beast Boy, both members of the previous Teen Titans group that had their Tim Drake in its ranks, opt to join Savior in finding the Super Sons, albeit on the condition that Superboy only be de-powered or contained instead of outright killed. Meanwhile, Starfire, Aqualad and Kid Flash, none of whom have worked with either Tim Drake in past, decide to reach Robin and Superboy before their friends can.
After defusing the Savior situation, the Teen Titans and Superboy wind up at the Watchtower to recover and take everything in. Upon sitting down, Robin holds a vote to make Superboy a real half-member of the Teen Titans, at which point he'll be able to join on as a member full time when the Boy of Steel turns 13. Both Superboy and Robin are convinced that it's an easy sell, given that Superboy has helped them in the past and the Boy Wonder has a clear respect for his friend. Unfortunately, the rest of the Teen Titans don't support Robin's vote, much to his shock.
Before Superboy can get any ideas about what he did wrong, Starfire explains that the events with Savior didn't lead to this outcome. The Titans clarify that this situation has made them all decide to figure things out between the six of them and how to work better as a team, and to bring any new members in when they still have trouble gelling as a cohesive unit would be less than ideal.
There's nothing really stopping the Teen Titans from extending another offer to Superboy once they've sorted themselves, but the damage has been done. Much like how his father felt alone growing up, Superboy now feels a similar sense of isolation after the only people his age who understood what he was going through rejected him. And even though Robin and Superboy have sworn to protect one another to make sure their prophesied dark future doesn't come to pass, the Boy of Steel still can't help but feel all alone in the world.