Honestly people who hate Ijun are just stupid! He was kept in the dark for so long and I think that readers forget that he doesn't know everything that we do. Of course he would be skeptical after being told that everything he'd ever known was a lie that was purposefully being kept from him. He clearly just directed his hatred at Siyeon because he felt hurt by her the most.
who is this DIVA!!
No, but seriously, Ethan is just that girly, I fear. He's just letting his intrusive thoughts win