Setting Boundaries vs. Being "Controlling"

[Alvar]

When trying to decide how to deal with a behavior they have deemed unacceptable, I encourage Nice Guys to apply the Healthy Male Rule. Following this rule of thumb, they simply ask themselves, "How would a healthy male handle this situation?" For some reason, just asking this question connects them with their intuitive wisdom and helps them access the power they need to respond appropriately.
Once the Nice Guy knows he can set a boundary any time he needs to, he can let people move toward him, get close, have feelings, be sexual, and so on. He can let these things happen because he is confident that at any point, if he begins to feel uncomfortable, he can say "stop," "no," or "slow down," or can remove himself. He can do whatever he needs to do to take care of himself.

Read chapter 7 of Glover's No More M.Nice Guy for more. However, from your example it sounds like you may be taking too much responsibility for her emotions and actions. Unless you have reason to believe that she is provoking you, you must accept that some days she will feel cold towards you, she may want to distance herself; and your job there is to respect her, as she is.