Britney Spears and Sam Asghari have decided to call it quits one year after they tied the knot, a source tells ET that the ending of the pop star's conservatorship had much to do with the shifting of the couple's dynamic.Amid tabloid reports that the actor has allegedly threatened to release embarrassing information or materials about Britney unless concessions are made in their prenup that would allow Sam to get more money out of the divorce — which he vehemently denied — a source sheds some light on how the couple's relationship changed after Jamie Spears filed court documents to end his daughter's conservatorship.«Britney could be argumentative at times, but also felt like Sam didn't let her do a lot of things without him,» the source tells ET. «Before Britney's conservatorship ended, Sam was very supportive.