| Quote #1
Prior: I was scared, Lou. [...] That you'll leave me (1.4.51).
Prior has hidden the fact that he has a lesion from Louis. He knows Louis very well and senses that the difficult realities of living with a person with AIDS might drive Louis to abandon and betray him. It seems that Prior's fears are justified.
| Quote #2
Louis: Rabbi, what does the Holy Writ say about someone who abandons someone he loves at a time of great need? (1.5.49).
Louis is struggling with his instinct to abandon Prior. He's already feeling guilty about the act of betrayal he will eventually commit.
| Quote #3
Louis: What if I walked out on this? Would you hate me forever?"
Louis is contemplating deserting Prior, and he's feeling incredibly guilty. Prior admits that he wouldn't forgive Louis if he did this. The kiss on the forehead shows Prior's immense love for Louis, perhaps making the betrayal all the worse.