In they weren’t featured on Legend of Korra as a couple, and Suki wasn’t featured at all.
While fans would still like to know more about what happened to them in canon, there are still many good reasons why these two were great together as well as some reasons why they don’t make a lot of sense.
Weren’t: Because Sokka held sexist beliefs at first
Sokka at the beginning of the series isn’t nearly as likable as later in the show. At first, he is rather sexist and demeaning to women including to Katara and then to Suki and the other Kyoshi warriors.
Luckily, he does change his mind and becomes much more respectful and believes in equality, but the fact that Suki would so quickly be interested in him after he was so sexist doesn't make a lot of sense.
Were: Suki didn’t let Sokka disrespect her
While on the one hand, it seems strange that Suki would be quickly okay with Sokka’s behavior, she at least doesn’t condone it.
She shows Sokka the error of his ways by proving that she’s a much more skilled warrior than he is. She’s not going to let herself be disrespected, and it’s not until later in the series that these two actually get together anyway.
Weren’t: Suki was put too much in a love interest role
Suki is a great character from The Last Airbender, but she’s also one of the more underrated ones. This is because she doesn’t get as much screen time or scenes as Team Avatar or villains like Zuko and Azula. While at times she helps Team Avatar, she's cast as a love interest role for Sokka.
This is unfortunate because she had a lot of potential and was really interesting as the leader of the Kyoshi warriors.
Were: They were both non-benders
In many ways, Sokka and Suki had a lot in common. For one thing, they were both non-benders who had learned skills to fight without needing bending. Given that Sokka particularly often felt a bit out of place with his lack of bending ability, being with someone who was also a non-bender would make a lot of sense for him.
They would have been able to relate in this way and wouldn’t have had to worry about power imbalances as far as natural ability went. This seems like a better match for Sokka because of this.
Weren’t: We didn’t get to see enough of their relationship
One of the main reasons why it doesn’t seem like Sokka and Suki were soulmates is that we just don’t see that much of their relationship.
Because of this, it seems like the creators didn’t intend to make these two canon or to be together in the end as more details about the other of Team Avatar and their relationship are given. The fact that Sokka and Suki's relationship is left so ambiguous doesn't bode well for them.
Were: They had really good chemistry
While we sadly don’t get enough scenes between these two, the scenes that were shown had them getting along really well after their initial meeting.
They seemed to click overall based on their personalities, and they had a good and easy chemistry. It doesn’t seem like there would be all that many huge conflicts in their relationship.
Weren’t: Sokka seemed more in love with Yue
One of the main reasons that Sokka and Suki don’t seem to be soulmates is the storyline with Yue. Sokka seemed to have stronger feelings for her, and given the tragic way she left him, it makes sense he would hold onto her memory for a long time.
While this doesn't mean Sokka couldn’t love again, it does make his relationship with Suki seem less impactful. It was a bit awkward to watch him try to deal with this and get over Yue relatively quickly.
Were: Because they were both really talented warriors
Another reason why Sokka and Suki would make a great couple is that they had so much in common as far as skill sets and perspectives on the world.
They were both talented warriors in their own ways, and being able to protect people in this way meant a lot to them both. It seems that because of this that they would have similar outlooks that could help them bond, and they could also enjoy things like training together.
Weren’t: Because they might have been better with other people
While Sokka and Suki are overall a pretty good couple, it seems like they might have been a better match with other people. Sokka seemed to have stronger feelings for Yue, and there's also a good argument to be made for him and Toph being together in adulthood.
Suki isn’t shown as having any other romantic relationships, but it’s not hard to imagine her being happy with someone else, possibly one of the other Kyoshi warriors.
Were: There was balance in their relationship
While at first Sokka assumes that women aren’t as capable as men, he quickly sees this isn’t the case. After this moment, these two seem pretty evenly matched in many ways.
They are both talented warriors and leaders, and they have similar but different personalities that complement one another. Sokka is funny and a bit goofy where Suki is more serious but also enjoys having a good time.