1. Surely there are times when a woman goes through some conditions of bodily weakness and fatigue of the mind. Such that Allah has relieved her of some of her compulsory worships during that period; Allah has totally pardoned her from praying, and has postponed the days of fasting for her within this break to a later date until she regains her health and becomes normal in her temperament once more. Thus, during these days, treat her in a godly manner. Just as Allah has relieved her of the duties, you should also lessen your demands and instructions from her during those days.
2. Voicing a limit or a boundary is not the same as a demand. It's telling someone what you prefer, where you stand on something. You are not demanding anything, or telling them they are wrong. You are just asserting your own values, your desires or your limits.
3. Sometimes the boundaries need reinforcing from time to time. This may sound like a parent-child relationship - and it is that way. But we are not doing it in an authoritarian way, we are doing it in a friendly, supportive way. But we are also being assertive about our boundaries being understood and respected.