A/N: This is for the 5 drabbles challenge for the prompt 'selfless'.
The truth was simple. He wanted to protect her from his brethren and the Dark Lord, and the best way to do that was to let her go. He didn't want to, but it was for the best.
"Why, Severus? I thought we were getting on really well," she asked.
"We are, but...the Dark Lord and my brethren have noticed our relationship. I can't risk losing you, Emmy. They always use the people we love against us. What do you think happened to Mary?"
"She was killed in an accident," she said, her brow furrowed.
He shook his head almost violently, "They found out that Regulus was in love with her and when he refused an order they kidnapped her. He was forced to watch as they tortured and killed her. I can't have that happen to you. I love you too much," he confessed.
"They… oh Merlin. Oh poor Regulus," Emmeline said as tears filled her eyes.
Severus knew what he told her would hit her hard as she and Mary had once been very close friends, but it would be what she needed to see that he was right.
"Sev, I-I understand why you want to do this, but I don't want to lose you. Can't we just keep seeing each other in secret?" she asked desperately.
"I'm sorry, Emmy. If they even thought for one moment we were still together they wouldn't hesitate to take you. It's better if we make a clean break," he said, heartbroken at the tears falling down her face. "I promise that when this is all over I will come back to you."
"You better come back to me," she said, before standing on her tiptoes and pressing her lips to his.
Severus knew he would do anything to protect Emmeline, even if it meant sacrificing his own life to do it