he dint slap her cause of the call,
he slapped arjun and told him hw dld he do this wid purvi,he dint tell purvi to cum along wid him,he just left,if he wld b doubting purvi,he wld have fought and slap her,but he slpped arjun,cause he found him the culprit of ppurvi condition,as onir stated purvi was in bad shape whn she reached kolkatta