He didn't want her after she was denied and rejected. She chose someone else over him. He knew it was BS and made that mistake before he already knew the outcome. In the end, he would be lying and cheating himself to think it would change.
She had been lied to, cheated on and still went back it made no sense. Why would she spread that pain and misery to others. He saw good in her, but all he got was her worse. From having a crush to being a friend; he eventually shut down, turned his back walked away.
Saved himself from hurt and pain nothing left to remain. Hoping to find someone that loves them self and him as well.