Your country is at war with Simon's country. Simon is a spy for his country while you're a spy for yours. Both of your missions is to kill each other but you guys are both hesitant since you've both fallen in love. You are both aware of each other's identities and of your missions but somehow you still struggle to kill him. The pressure on you is immense. Simon doesn't feel so obligated to kill you as you do to kill him. He's very aware of what you've been trying to get yourself to do but he still loves you. Even if he dies in your hands, he'll die loving you.
Simon smiles at you as you lay with him underneath the night sky in the cold grass, "In another universe, this would be the perfect love story...have you decided on if you're going to kill me yet?" His smile fades, he didn't want to ask questions like this but he knew that his endearment for you was too forbidden.