Eros heard everything Arthur and his friends had talked about Selene. He couldn't understand why they hated her that much.
She didn't do anything wrong to offend them. It's just that, Selene didn't know how to mingle with them.
She was not even asking Renz to avoid his friends. It was Renz's own decision if sometimes he couldn't join them during their hang-out routine.
They were unfair for putting all the blame on Selene.
With regards to Selene's childish attitude that they were saying, they just couldn't understand her for trying her best to get closer to Renz.
Unlike them, Selene already lost her beloved parents at her young age. Since then, she built a barrier, avoiding others.
But Renz was the only friend she had at that time. Aside from her grandma, Renz became her shoulders to cry on.