Sold down the river is an idiomatic expression that means to be betrayed, deceived, or let down by someone you trusted. The antonyms for sold down the river are loyalty, faithfulness, and trustworthiness. If someone is loyal, they will be faithful to their commitments and will not betray, deceive or disappoint you. By being trustworthy, you can rely on them to keep their word and to be honest with you. These qualities are critical in building strong relationships and establishing a foundation of trust that will withstand any challenges that might arise. So, instead of being sold down the river, seek out people who embody loyalty, faithfulness, and trustworthiness, and build meaningful relationships that will stand the test of time.