Why was Eris mad that she wasn't invited to the wedding?

Eris, the goddess of discord, was upset about not being invited to the wedding of Peleus and Thetis because it excluded her from a significant event, which fueled her desire for recognition and revenge. In retaliation, she threw a golden Apple inscribed with "To the fairest" into the gathering, sparking a rivalry among the goddesses that ultimately led to the Trojan War. Her actions highlighted her role as a catalyst for chaos and conflict among both mortals and deities.