Kazuto "Kirito" Kirigaya and Asuna Yūki are Sword Art Online's two most passionate lovers by far. Ever since their two years trapped in Aincrad, they've developed a bond so strong that they would live and die for each other. It's why SAO, despite its male: female ratio, is a romance anime, not a harem anime. It's also why anybody else who's ever been after Kirito's heart never stood a chance.
Of all the other girls who were interested in Kirito, Suguha "Leafa" Kirigaya had to be the most romantic. However, after the "Fairy Dance" Arc, her romantic feelings went largely unexplored. As controversial as her love for her cousin was, she doesn't deserve to go home empty-handed. Perhaps there's a hint to how her future pursuits of love could go within the narrative of SAO.
When Suguha was formally introduced in Season 1 Episode 15, "Return," it was readily apparent how she felt about Kazuto. She was flirty, though it could easily be interpreted as sisterly playfulness. This is probably why when she took things a step too far (eg spending the night in Kazuto's bed), her love interest never caught on. Regardless, the message was clear enough for the audience-- Suguha liked Kirito.
Despite Suguha's feelings, she remains well-aware of her standing with Kazuto. While she understands that it's wrong to have romantic relations with blood relatives, it doesn't stop her from longing for him. What does stop her, however, is her realization of how much Kazuto cares for Asuna and only has eyes for her. These two facts put together are what truly make her realize the two of them could never be. With this, she concedes defeat.
Suguha was able to distract from her wounded heart by playing Alfheim Online. In this game, she plays the powerful Sylph Leafa. She's fast and handy with her sword and her magic spells. She's also quick to make friends, as is shown during her first interaction with Kirito. For Suguha, ALO was a chance for all sorts of new opportunities.
Sadly, Leafa got a little too attached to Kirito. She never realized that it was actually Kazuto, so she ended up falling for him all over again. This made it utterly devastating when she realized the truth in episode 22, "The Grand Quest." Thankfully, the two of them were able to reconcile in Episode 23, "Bonds." After getting her heart broken twice, however, it's no wonder Suguha hasn't been quick to go looking for love again.
Suguha may not get her first love, but that doesn't mean it's the end for her. Her going after Kirito proves that she's at least open to the idea of being with someone besides her cousin. It's just a question of who can fill the role.
So far, the best option offered for Suguha by the SAO narrative is Shinichi "Recon" Nagata. He seems to like her, though she has trouble returning his feelings. She also may have been holding off on responding to his advances as long as she felt like she had a shot with someone else like Kazuto or Kirito. Now that both of those possibilities are out of the question, Recon might have a chance.
However it happens, it would be nice to see Suguha's more affectionate side get the development it deserves. She's one of the few girls in the main cast to try and follow through on her romantic feelings. To have her go through everything she did in the "Fairy Dance" Arc just be another one of Kirito's friends would be a waste.
