I'm struggling to understand how the bolded part in the below sentence changes the meaning of the sentence.
I think that 狭さ refers to narrowness(in context that they are both walking close together in a very tight space), but I am not sure which に this is and how it is modifying the rest of the sentence.
七菜海のリアクションが、可愛くてそれでなくても、この狭さに、密着でドキドキの俺は、悟れまいと尤もらしいことを言う
