True friendship is never serene.

Taken at face value, the line suggests that genuine friendship is not a placid, untroubled state but an emotionally charged bond that invites anxiety, jealousy, longing, and conflict alongside affection. “Never serene” implies that intimacy makes one vulnerable: friends matter enough to disturb one’s composure, whether through fear of loss, the pain of misunderstanding, or the demands of loyalty. Read in the spirit of Sévigné’s epistolary wit and psychological acuity, the aphorism values friendship precisely for its capacity to unsettle—because it engages the whole person rather than remaining a polite, indifferent sociability.