He had married two years ago, and had taken his wife to live at Styles, though I entertained a shrewd suspicion that he would have preferred his mother to increase his allowance, which would have enabled him to have a home of his own. 
His allowance was less than generous thus it warranted an increase.  
mnli hypothesis: His allowance was less than generous thus it warranted an increase.   premise: He had married two years ago, and had taken his wife to live at Styles, though I entertained a shrewd suspicion that he would have preferred his mother to increase his allowance, which would have enabled him to have a home of his own. 