Two girls are "friends". If two girls like one guy. But the guy only likes one girl. Will the left out girl try to ruin the couple?

Assuming the left out girl has a resentful and nasty personality.

This is happening to me now. I feel like the girl left out is giving my crush bad relationship advice.
Two girls are "friends". If two girls like one guy. But the guy only likes one girl. Will the left out girl try to ruin the couple?
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