We've been together for two years, but there's been no sex for a month. Is she manipulating me or is it an honest refusal?

Refusal of sex in itself is not manipulation: no one owes sex to a partner, neither in marriage nor in long-term relationships, and even a one-time consent does not mean consent in the future. Manipulation begins where refusal becomes part of a control scheme — when a person is deliberately deprived not only of sex, but also of affection, attention, communication, in order to punish, subdue, or make them feel guilty. If a partner simply does not want intimacy due to fatigue or stress, this is a reason for conversation, not accusations. If you see coldness and 'crumbs' of attention as a way to control you, this is no longer about sex, but about a toxic relationship. It is also important that the partner does not hide their unwillingness: you have the right to know what is happening. If you cannot figure it out on your own, it is worth consulting a psychologist or a relationship specialist.