SoraNo character has as an important of an influence on Naminé as Sora. He is the catalyst for her character development as well as the center of the purpose she created for her own existence. Sora touches Naminé's heart much like he does to all the other characters of the series. She was alone for so long that she was starting to drown in her intense feelings. She grimly carried out what was asked of her by Marluxia and the guilt only piled on top of her already mounding negative emotions. Seeing Sora fight so hard for her sake caused her to reconsider her choices up until that point and confront him with the truth. It may have been based on fake emotion, but he cared about her and fought through many obstacles in order to reach her. Naminé did not want to hurt the only person in the world who cared about her existence. Sora's forgiveness, however, is what completely changes everything. She can hardly believe that someone would forgive her actions or that she even deserved forgiveness to begin with. Hearing Sora tell her that he still cared about her despite knowing all the memories were fake made her very happy. Naminé's resolve is thus changed from thereon out. She is willing to risk her own life to protect him from both Larxene and Marluxia and cares about him so much that she ignores her own desire to stay important to him in order to fulfill his wishes to have his old memories returned in exchange for forgetting her. I am sure that she knew he would not choose to remain with her but I suppose that goes to show how happy she was to finally have an emotional bond with someone. Despite her heart calling out to Roxas and Xion, she still keeps firm to her resolve to completely recover Sora's memories and therefore facilitates the process of their return to his heart. Nearly everything that Naminé does after meeting Sora is for his sake. He was, after all, the only person to care about her on his own.
Riku ReplicaRiku Replica is another character who had his memories manipulated by Naminé's powers. In fact, he had the exact same memories implanted in him as Sora, causing the two to be in conflict frequently. Naminé feels very guilty about this as well as she is clearly angry when Larxene and Axel bring it up in front of her. Riku Replica promises her that he will always protect her and get rid of anything that makes her sad. Even after knowing he is merely a replica with fake memories, he still chooses to protect Naminé in the end because that is all he has. I think Naminé feels guilty for manipulating his memories and thus causing him to take such extreme measures for his sake, but she never gives the impression that she cares for him as much as Sora. It is possible that she feels less responsibility because he never had any memories to begin with, whereas she actually had to change Sora's memories. Regardless, Riku Replica was the only other person besides for Sora to choose to keep caring for Naminé even after knowing the truth and I am sure on some level she does appreciate that fact.
RoxasNaminé appears to take a special interest in Roxas as she goes out of her way and against orders to meet him. She even tells him that she wanted to meet him, even if it was only once. She was probably interested because he was one of two nobodies that she met similar to herself. She was also asked by Xion to look over him as well. Most of her motivation, I feel, lies in the fact that she knew his situation was similar to her own, though. He was struggling to find an identity. He did not know who he was or what his purpose was, much like how she felt when she was born. Naminé insists on Roxas knowing the truth before he becomes one with Sora and attempts to ease his mind about the process. She promises him that they will meet again someday soon, even if they no longer recognize each other, and talk about everything. Just like she promised, the two do meet and talk again outside of their counterparts' bodies one last time. They promise to stay together so long as Sora and Kairi stay together and are satisfied at last to become whole with their counterparts. It seems that they have an unspoken sense of understanding because of their similar situations as well as their close connections to each other through Sora and Kairi. At the end of Kingdom Hearts II, Naminé and Roxas are seen smiling at each other through Sora and Kairi, implying that they truly would live on together. There seems to be a lot of online support for their relationship in a romantic sense, but nothing has been stated officially in the games. Roxas does seem to care for Naminé at least a little though as he demanded that she be released when she was being restrained by DiZ in the mansion.