Don't really follow the Manga but decided to pop into the chapter and really lol they spend the entire chapter on a erotica *** scene what's so deep about that. I hope not Touka :Sparks:
You need to understand their relationship and its progression from the beginning to understand the significance of the chapter. Personally, I am a guy who is usually completely apathetic to pairings and romance in any form but I was deeply moved by this chapter, probably for the first time in my life over a pairing – such is the quality of this aspect of Ishida’s manga.
Kaneki and Touka’s relationship in the TG is one with a lot of symbolic, pictorial depiction – the type where what is left unsaid in their interactions has more meaning than what isn’t – that I myself did not notice on the first reading of TG.
As a single example consider the small detail of Kaneki crying in this chapter.
First, this is a reference to the first time Haise sees Touka at the beginning of :re where, despite a lack memories, his repressed feelings for Touka as Kaneki, who did not know she was alive, bubble over and he can't even understand why he starts crying. It is touching to see him react by crying upon finally learning that his feelings were mutual – in fact he seems to be in disbelief – again notice the small detail of Kaneki repeatedly questioning "is this real" in the chapter – which is typical of his character, this is a guy who thinks that only by suicidal sacrifice can he earn the affections of the people he loves.
Second, it is consistent with the fact that Touka is one of the handful of people in this manga who has brought him to tears – the last time was when she subtly told him that she did not want him to die just before his suicidal fight with Arima – and she is literally the only person to have done so multiple times now. Whether it is because she causes him pain, as when she tries to deny him his suicidal repose, or happiness, as she has now in making him feel loved in this manner for the first time in his life, Touka brings Kaneki to tears.
Now, I could write a long but mediocre essay (I’m not good at literary analysis of feelings and that type of stuff to be honest, my forte is philosophy) that does not come close to doing this chapter of the manga justice but I have final exams this coming week. If you want to learn more about the literary significance of this chapter I will make a very rare recommendation – go read analyses of it on tumblr, many of the folk there understand Touken better than I.