Using a cell phone while driving is a poor idea. Not only do you endanger yourself, the other occupants of your car and the other drivers on the road. This can also bring down the curtain on a relationship that's already in trouble, suggests University of Minnesota professor of family social science Paul Rosenblatt, in an article published in Family Science Review and noted in UMN's University News Service (http://www1.umn.edu/news/news-releases/2010/UR_CONTENT_202137.html) .
A conversation minus the visual cues -- gestures, facial expressions and posture -- combined with poor reception and pregnant pauses (the person on the other end doesn't know that you are silent because you're trying to avoid a pot hole) can lead to serious misunderstandings. If the relationship is already tenuous, Rosenblatt suggests, this could be the last straw.
By the same token, if you've just starting dating someone and don't know each other well, a garbled call could end something that seemed promising.