My Sister's Boyfriend | Yeonbin

f o r t y t h r e e

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Beomgyu’s knuckles were white as he gripped his phone, scrolling mindlessly through social media, his jaw clenched tight. Every post, every reminder of Soobin or Yeonjun made his blood boil. He had told himself that after spilling the truth about what those two had done, he would feel better. That maybe, by exposing their betrayal, he could protect Kara from the heartbreak they deserved to feel. But now, weeks later, all he felt was a gnawing frustration that refused to go away.

He tossed his phone onto his bed, running his hand through his hair in frustration. How could they do that to her? Kara didn’t deserve this, least of all from her own brother and Yeonjun—the guy who always acted like he was so perfect. Beomgyu had known something was off with them, the weird glances, the way they’d act cagey whenever Kara was around. He hadn’t wanted to believe it at first, but once he found out the truth... well, there was no holding back.

He still remembered the look on Kara’s face when he told her. The shock, the disbelief, and finally, the way her expression had crumbled into hurt. Seeing her like that had been enough to push him over the edge. It was why he had made sure everyone knew. Yeonjun and Soobin weren’t going to get away with what they did. Not on his watch.

But the anger still simmered, unresolved, even though the damage had been done. Beomgyu had thought maybe it would fade after a while, but every time he saw Kara’s distant, distracted look, the way she seemed so weighed down by everything, it flared up again. He hated that she was hurting because of them. And he hated that, despite everything, she still cared so much about her brother and Yeonjun.

"Why do you keep caring about them?" he muttered to himself, pacing around his room. He had tried to be there for her, offering support whenever she needed it, but it never felt like enough. He wanted to fix things for her, to make it so that she didn’t have to feel this way. He wanted to be the one who helped her move past it.

But there was something else gnawing at him, something deeper. His crush on Kara, the one he had tried to push aside for so long, was becoming harder to ignore. It wasn’t just that he hated seeing her hurt—he hated that he wasn’t the one she turned to when things went wrong. As much as he wanted to deny it, a part of him wished she would notice him the way she noticed Soobin and Yeonjun, even after everything they had done.

Beomgyu groaned, frustrated with himself. "This isn’t about you," he muttered under his breath. But he couldn’t help it. Every time he was around Kara, the feelings grew stronger, and the jealousy twisted inside him.

He was angry—at Soobin, at Yeonjun, at himself. How could they betray her like that? And why was he the only one who seemed to care enough to call them out for it?

Slumping onto his bed, Beomgyu stared up at the ceiling, his mind racing. He knew he should talk to Kara, maybe even apologize for making things more complicated by telling everyone. But part of him didn’t regret it at all. Someone needed to stand up for her, and if that meant exposing Soobin and Yeonjun, then so be it.

Still, his chest tightened at the thought of Kara pulling away from him because of what he did. What if she saw him as the bad guy now? What if, in trying to protect her, he had only made things worse?

With a sigh, Beomgyu sat up, grabbing his phone again. Maybe he needed to confront Kara directly. He hadn’t spoken to him since everything went down, and the tension was suffocating. Beomgyu couldn’t keep holding onto this anger—it was eating him alive.