Sirius lives, eventual Harry/Susan
Despite living together, Sirius and Harry hardly saw each other. Harry was nearing the end of his Auror training and when he came home, he went straight to bed. Every Friday night, if Harry wasn't on an assignment, Sirius insisted they eat dinner together, but even then, Harry's head usually drooped toward his meal. One time he'd even face-planted in his pasta, but instead of laughing, Sirius' heart broke.
In the beginning, Ginny had accompanied them at dinner, and then would follow Harry up to his room. Sirius, who might have been a masochist, listened at the door once but heard only Harry's snores. Judging by Ginny's expression when she'd emerge from the room long after Harry went to work, nothing sexual ever happened on those nights.
"It'll get better once he's an actual Auror," Sirius offered, feeling some pity for her. "Right now they're trying to weed out the trainees who can't take it."
Ginny grunted and slammed a mug on the counter. "Yeah, and then he'll expect me to pop out kids." She looked around the kitchen. "Don't you have coffee?"
"We're tea drinkers," Sirius said apologetically. "I can spike it if you want."
"Yes, please," she said a bit too fervently.
She'd stopped coming to the house so often after that conversation. Privately, Sirius was hoping she and Harry would break up soon. He liked Ginny as a person, but he didn't think she and Harry were right for each other. They were better off as friends than as a couple.