Kinsey believed males do not represent two discrete populations, heterosexual and homosexual. The world is not to be divided into sheep and goats. It is a fundamental of taxonomy that nature rarely deals with discrete categories... The living world is a continuum in each and every one of its aspects. In essence there is no clear line between heterosexual and homosexual.
I guess, for this reason, many struggle with their sexuality. Although the struggle may be felt within, the struggle often comes from what society may thing, what your family may think, what will your friends think, and how people will react and treat you. Here, in the Doorman, the young man seems to struggle with his sexuality. He is drawn into unfamiliar passion.
I don't know if there is a thin line between heterosexual and homosexual. But, I know in itself is a struggle.