Severus watched Harry walk away and he just knew he would never be able to look at Potter in the same way again. He could not argue with the proof of what would happen in the future, he was living a dream, a dream that was going to end soon. Lily would marry Potter and that would be their son.
He took a steadying breath as Lily addressed him. He didn't want to upset his friend any more, "If you want to leave..." He didn't know what to do or say to make this better, it was hard enough for him to stay calm as it was. Potter had been making his time at Hogwarts a hell and it looked like it would not end any time soon. He would not be allowed happiness in the future either.
"Your choice of course." He did not blame Lily, she was his friend and he would always love her even though she would pick Potter over him.