Reluctance is the feeling, or the showing, of I do not really want to. Someone with reluctance says yes slowly, or only after a push. You meet it in news and in slightly careful talk: there is reluctance to raise prices; she agreed with reluctance. It names the unwillingness as a thing you can point to, not just the describing word reluctant. Though actually, it is not always a hard no. Often the person will do the thing — they just let you feel the drag. A long pause or a sigh does the same work without the noun. It sits a step more formal than they didn't want to, which is why schools and newspapers like it. The very old verb hiding inside it, reluct, to struggle against, is almost gone; this noun and the adjective kept the job.