Until relatively recently, social psychologists have limited their study of interpersonal attraction to initial encounters or first impressions. why?

The answer is A. Long-term relationship is more difficult to study scientifically.
Now the explanation of a faithful relationship, as stated by Wikipedia, is an "Interpersonal relationship based upon a mutually agreed-upon commitment to one another involving exclusivity, love, trust, honesty, openness, or some other agreed-upon behavior."

Ifound this on google “the change in control meant as house minority leader, pelosi was widely expected to become speaker of the house in the next congress. on november 16, 2006, the democratic caucus unanimously chose pelosi as the democratic candidate for speaker.” i hope this

Hope this will !