Maintain relates to continuing to have something (tangible or intangible) Remain relates to continuing to be something. Maintain: a friendship, your intelligence, connections, a sense of humour, your wealth. Remain: happy, sad, hopeful, rich, poor. You can use friends after both, but with a different meaning: To maintain a friend is to keep a friend that you have. To remain a friend is to continue to be a friend to someone else

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