I am studying the effect of changes in household state on transport mode changes in people's life trajectories. My model is such that each observation I have is a 2-year period in a person's life. My DV is mode change, and it is binary: has there been a mode change in the period? My two predictors are similarly binary: has the respondent married in the period? has the respondent had a child in the period? I am interested in whether these two events have a significant relationship with the likelihood that one changes transport mode.
Question: I do know that it is impossible that someone who is already married marries again. Thus, I am confused about whether I should filter out observation windows in which the respondent is married at the beginning. My worry is that these observations (which happen most often) may be biasing my overall results in the regression. Does this make sense?