Sex and Relationship

Patient: My wife gave birth to our son about 9 months ago and we have not had sex in about 11 months. 3 days ago we had sex and I felt like she has been having sex on a regular as I have not been around for over 7 months. I felt like it was much easier than I anticipated as I was expecting a little difficulty and pain on her part but there was none of both so I feel she has been cheating on me but want to be sure