The latest episode of Young Justice makes it clear the newly engaged Miss Martian and Superboy have many issues they need to work out before they get married. The two heroes have enjoyed an on-again, off-again romance over the course of three seasons, but the latest setback in their relationship may prove to be the straw that broke the camel's back.
Superboy and M'gann M'orzz began to bond shortly after they first met, during the first season of Young Justice. Both had trouble fitting in among normal teenagers, due to M'gann being new to Earth and Superboy being a clone of Superman and Lex Luthor who had never had a proper childhood. It was M'gann who suggested Superboy adopt the first name of Conner, taking it from the boyfriend of the sitcom heroine on whom she based her own Earthling persona. Superboy was also the first person to learn M'Gann was a member of the usually violent White Martian race - a secret he kept until she was ready to reveal it to the rest of the team, along with his own connection to Lex Luthor.
The two heroes broke up between season 1 and season 2 of Young Justice, after Superboy objected to M'gann using her telepathy to mess with the minds of supervillains. Given how his own memories had been altered by the scientists who created him, he had strong opinions on such things happening to other people. When Conner learned M'gann had responded by erasing his memories of their fighting because she couldn't stand having him mad at her, he dumped her. The two later reconciled, however, and the season 3 premiere revealed the two had moved-in together, just before Conner proposed to M'gann.
The latest episode of Young Justice, "Terminus," saw the long-running argument between the two heroes over the ethics of telepathy and lying flare up once more. One episode earlier in "Anti-Social Pathologies," it was revealed M'gann had been secretly coordinating with Batman, Nightwing, Oracle and Robin, who had publicly cut ties with the Justice League, so they could secretly battle the metahuman trafficking rings run by The Light. This resulted in what seemed to be seven separate teams (including Beast Boy's newly formed Outsiders) truly being run by one secret society of superheroes.
When Conner confronted M'gann on how she had lied to him again, she defended her actions by claiming she and the rest of the leaders were trying to protect their teammates and offer them deniability should their plan be exposed to the public. Conner sarcastically pointed out her actions didn't do much to protect Beast Boy's feelings when he found out some of the Outsiders earliest victories had been staged events organized by Batman. Conner went on to point out several other occasions when keeping secrets had hurt them and their friends. When M'gann asked if he had truly forgiven her for what she had done in the past, Conner responded "forgiving doesn't mean forgetting" and said lying to the ones you love hurt just as much as any telepathic attack.
With three episodes of Young Justice left in this season, it remains to be seen if Superboy and Miss Martian can reconcile their differences or if their wedding will be delayed or even called off. The two have a long and loving history and have already overcome many obstacles together. Unfortunately, for all the power the two heroes have individually, repairing a broken trust may be beyond even their abilities.