Having a baby & argument

So my guy friend and his girl are have a baby but the girlfriend continually talking to other guy send them booty pic call other guys baby and my guy friend doesnt want to  leave her they get into it when he brig the problems up and she start bugging the fuck out the twll him to chill an all of this stuff he give her way to much attention and he get nothing back she to busy text or no facebook  And tell him he should leave her he comes nto me for advise but i dont know what to say cause the girl friens stubborn af. Help me please tell him what he should do.