Relationship Touka and Kaneki?

Kaneki in turn viewed her as someone important to him and tried to put her out of harm's way. He responded aggressively to anyone who had hurt her, shown when he broke half of Ayato's bones for hurting Touka and held back from killing him as it would only hurt her more.

Upon leaving Anteiku, Kaneki stayed true to his intent to preserve her safety and protect her, shown when he refused to allow her to come with him and avoided her during the months he was away. This caused Touka to often wonder of his whereabouts and wanted to meet him again, as observed by Hinami. Their first reunion when he returned to the 20th ward concluded in an argument and Touka beating him up.

Years later as Sasaki, he visited :re and experienced a sense of déjà vu. He subconsciously remembered her, the taste of her coffee had brought him to tears and he thought she was very beautiful. From then, Sasaki developed an infatuation for Touka — he often thought of her and visited :re on multiple occasions. She noted that at the time, he looked at her with the same gaze he looked at Rize with in the past. Nonetheless, Touka believed it was best for Sasaki to not remember who he was, but she agreed that if his memories returned, he was welcome in :re.

After regaining his memories, Kaneki met Touka in Cochlea during the Kirishima's fight with Arima. He originally planned to die at the hands of Arima, however he was brought to tears once again when she told him she would see him later, a cruel act in his mind. After the Cochlea raid, Kaneki initially reverted back to his post-Aogiri treatment towards her, continuing his distance from her. After a month, they finally conversed in a friendly manner in :re, though not ending well, they agreed to have the same ideals towards ghouls and humans' interactions. After Goat was formed, he repeatedly excluded her from combat and operations of the organization, much to her disappointment and confusion. Following the Clown Siege, during another private talk, she asked about this and his virginity — causing him some obvious nervousness and discomfort. Together, they discovered their fears of losing the other were mutual. And in the conversation she mentioned the look he gave her as Sasaki, a look that embarrassed Kaneki but one that Touka admitted made her happy, indicating her romantic feelings for him. Afterward, he acknowledged her by asking her to go with him to a Goat meeting.

Successfully escaping an ambush, Kaneki and Touka took shelter in an abandoned building and consummated their relationship after a kiss, officially becoming lovers. As a memento of her, he received her parent's ring, one that served as a source of strength for her during difficult times. Realizing he truly loved Touka the two became more and more intimate. Kaneki then asked her to marry him in a ghoul ceremony after she revealed she was pregnant with his child.

After being dismembered by Suzuya and Hanbee and cornered by the Oggai, Kaneki started to hallucinate — the multiple personalities of him clash over the various choices that caused his defeat and he was close to completely giving up. However, when one of them pointed out that they would never see Touka again, all of them came into an agreement to continue to fight for survival in order to see her again, showing how important Touka had become in Kaneki's mind.