"I'm feeling I'm not enough for them and that's why they want others..." Is the #1 reason why women stay in open relationships, or a relationship that is unsatisfying. Because they think that it is perhaps their cause.
Requirements have nothing to do with anyone other than yourself. They are free of co-dependency, full of responsibility, and nourish and support you to create healthy relationships. They help people actually love and be in relationship with the true you.