As much as you felt you were best friends and the marriage was great, there obviously were some problems. I have trouble with the privacy thing, both her feeling she needed to protect and your wanting to know (thinking about it at all) and yet not knowing. It sounds like communication was not open in your relationship and I would work on that if I wanted to save the marriage. It is my experience that secrets in relationship tend to grow toxic mold; true trust and communication are like sunshine and keep the mold at bay.