倦怠期 is usually translated into English as “lethargic period”. Just thought I’d add it since Louis wasn’t sure. It’s not really a term that exists in the UK or even overseas for that matter. Sometimes in a relationship, you feel like you don’t know what your feelings are towards the other person. Fundamentally speaking, you probably still like them but you feel less enthusiastic about them. This kind of stuff is normal in a relationship though I guess. (Apologies if I spelled his name wrong)