noun
stage of ennui; period of lassitude; rut
Often used for the phase in a marriage or long-term relationship when passion fades and monotony sets in. Can also apply to work or other long-term situations.
結婚して5年、倦怠期に入ったように感じる。
After five years of marriage, I feel like we've entered a rut.
仕
Feeling a period of lassitude at work, I'm thinking of changing jobs.