In the world of anime, there are a lot of ships which fans support. When it came to Naruto, the fan-made love triangle between Naruto, Sakura, and Hinata was intense. Other series like One Piece and Bleach have also had their share of shipping wars. When it comes to Attack on Titan, the most popular coupling lies with Eren Yeager and Mikasa, but it doesn't look like the series' creator is totally behind the pairing.
In the past, Hajime Isayama has spoken about whether Eren has developed more romantic feelings for Mikasa. In the third volume of Gekkan Shingeki no Kyojin, Hajime addressed the issue point-blank, and you can read his response below:
"For Eren, rather than a lover, Mikasa's presence is more like a mother to him. The love towards a mother is considered valuable [precious], however at the same time, there are annoying parts as well [laugh]," the creator said.
"Just like towards one's actual mother, Eren will start to grow up when he becomes independent [move away/not dependent on] from Mikasa, I might draw this scene one day."
Judging by Hajime's answer, it does not look like Eren's hormonal surges have pointed him in Mikasa's direction. The pair are still close with one another given their shared upbringings, but Eren still looks to Mikasa as a caretaker. When the pair were younger, Eren often looked after his adoptive sister once her parents were murdered, but Mikasa separated herself from such codependence when they joined the military. Mikasa became a strong soldier who would follow Eren into the heart of war if he asked, and the boy has interpreted that choice as a motherly one.
Still, it seems like Eren could one day develop less-than-platonic feelings for Mikasa. Hajime hinted the protagonist will become independent enough one day to see his longtime friend in a new light, and the shift may be enough to make Eren fall for Mikasa's quiet charm.
You can read the synopsis for Attack on Titan season two below:
Eren Jaeger swore to wipe out every last Titan, but in a battle for his life he wound up becoming the thing he hates most. With his new powers, he fights for humanity's freedom facing the monsters that threaten his home. After a bittersweet victory against the Female Titan, Eren finds no time to rest—a horde of Titans is approaching Wall Rose and the battle for humanity continues!