Ask her why. We don't know. Maybe she's getting it someplace else. Or it takes her a week to recover from the last time. Or she resents something you do. Or she's just not interested in sex, but wants to make an attempt to satisfy you weekly. Or she's tired. Or too busy. Or feels fat and undesirable. O anything else! You have to communicate if you want your marriage to work. Communicate with her, not us.