In Chapter 18, Marlowe is conflicted about his friendship with King, why?

Marlowe’s friendship with the King – and the hatred that Lieutenant Grey has for him – brings him to the attention of Colonel Smedly-Taylor, who says that while he can’t order him to stop associating with the King, he would strongly suggest that Marlowe do so. Marlowe finds himself feeling uncomfortable about sitting with the King at the theater, while at the same time feeling guilty that he should be concerned or ashamed about being seen with a man he considers his friend. Marlowe’s proper upper class upbringing is at odds with the genuine affection and friendship he feels for the King, and he finds it difficult to balance the two.