Is breaking a covenant with God after repentance and weeping unforgivable, and what should be done now?

Sincere repentance (Tawbah Nasuh) for this sin is obligatory. The door to repentance is open and will not close until the sun rises from the west. Allah accepts repentance no matter how many times the sin is repeated, and the one who repents is like one who never sinned, as the Prophet, peace and blessings be upon him, said: "The one who repents from a sin is like one who has no sin." If you made a vow and uttered it, then you must offer an expiation for an oath (kaffarat yameen).