Committed spouses look at attractive people less

Scientific American - People in Love are Blind to Pretty Faces

Usually people are distracted by attractive faces and perform poorly on reaction tests administered immediately after shown such faces. However, people in long-term relationships or marriages (or who were otherwise monogamous) who were primed with the thoughts of their beloved did not perform poorly on the same reaction tests versus the control group. Interestingly, people averted their eyes from an attractive face more quickly than when they saw an average-looking face.