~一方だ (increasing unidirectionally)

The structure [plain-form verb]+一方だ (or formal copula ~一方である / polite ~一方です), literally 'only in one direction,' used to express that something is steadily increasing, worsening, or continuing in one direction without reversal. Examples: 悪化する一方だ ('only getting worse'), 増える一方だ ('keeps increasing'), 信頼は失われる一方である ('trust is only being lost'). Distinct from contrastive ~一方 ('on the other hand').