The mask permits Erik to interact with the external world, but it also prevents him from forming intimate connections. This is the central paradox of the story. In Chapter 27, he tells the Persian about his kiss with Christine:
I kissed her! I did! I kissed her! And she did not die of horror! She stayed beside me – as if it were perfectly natural – after I had kissed her like that, on her forehead. Oh, how good it is, Daroga, to kiss someone! You would not understand! My own poor, unhappy mother, Daroga, never let me kiss her – she recoiled from me and made me cover my face – nor did any other woman! So imagine! I was so happy that I burst into tears.
Until this moment, the Phantom avoided close relationships because he feared people would react to him with the same horror his mother expressed upon discovering his disfigurement. But at the end of the story, the Phantom unmasks himself to Christine and they "cried together" as he experienced "all the happiness a man could ever wish for."
Here the paradox is broken, Erik no longer needs the mask to connect with Christine, and she does not fear his face. This moment of emotional release marks the climax of their (mostly one-sided) love story.