Between protecting National City and her career in journalism, Kara Danvers hasn't had a ton of time for love on The CW's Supergirl. Her most serious non-platonic relationship so far was with Mon-El, though things didn't work out for them for reasons beyond their control. And while Melissa Benoist has indicated Supergirl's final season will focus on the slow burn romance between Kara and her new love interest William Dey, there's a case to be made that the show would be better of finally making Kara and Lena Luthor a canon couple instead.
Kara and Lena, otherwise known by their ship name, "Supercorp," are already one of Supergirl's most compelling couples, romantic or not. The pair were initially at odds when Lena made her debut in Season 2, as a result of her connection to Lex Luthor and his hatred of all things Kryptonian, but that quickly changed and the pair soon became close friends. Since then, their relationship has been complicated by Kara's need to keep her identity as Supergirl secret from Lena, despite her knowing all about Lena's trust issues after years of her dealings with Lex and her equally diabolical mother Lillian.
When Lex finally told Lena the truth before Kara could, it was such a big deal that Supergirl spent pretty much all of Season 5 unpacking the resulting emotional fallout and the way it spurred Lena into becoming a borderline villain. Forgiveness didn't come easy for either Lena or Kara after that, which is a testament to just how much their previous connection meant to one another. The fact they eventually rekindled ties and allowed their bond to evolve further shows how much both characters have matured since the show's earlier seasons and now have a firmer grasp of what it takes to make any type of adult relationship work.
Kara's blossoming romance with William is a healthy one based on mutual respect and the series has been careful not to rush into making them a couple. Still, with Supergirl Season 6 being the last season, it's hard to imagine the show will have the time to give their relationship much depth. Rather, those episodes might be better off devoted to exploring Kara and Lena's romantic feelings for one another and how their past makes it hard for them to trust each other with their hearts, in spite of their newly-repaired friendship. DC's Harley Quinn animated series showed just how great a storyline like that can be when it charted Harley and Poison Ivy's own journey to becoming a couple in Season 2.
Of course, Supergirl's writers have the right to take Kara's love life in whatever direction they deem fit in Season 6. They might even elect to end the show with her not being in a romantic relationship at all, which would be subversive in some ways. That said, Supergirl is a series that has long pushed the envelope for LGBTQ representation in superhero media, between having Kara's sister Alex come out as queer in Season 2 and introducing The CW's first transgender superhero, Dreamer, in Season 4. By ending things with Supercorp, the show would remain true to that cause, while also bringing Kara and Lena's personal arcs to a satisfying close.
Returning to The CW in mid-2021 for its final season, Supergirl stars Melissa Benoist as Kara Danvers, David Harewood as Martian Manhunter, Chyler Leigh as Alex Danvers, Nicole Maines as Dreamer, Jesse Rath as Brainiac-5 and more.