A so-called ratonalist leader once quipped " 100 tufts can unite together but not 2 braids can go together" meaning 100 tufts denotes 100 brahmins can work together (thesedays there are no brahmins only vermins) but 2 ladies cannot unite.
The relationship get soured between saas-bahu because if one look from mother's angle she feels that her grip over her son is lost after the entry of the bahu in their house. If you look from bahu 's angle, The moment she enters her in-laws house she is positioning herself as Chengiz Khan no matter who comes in her way. "Sirf Kallaas" that is the mantra. Moreover, the laws in India are heavily tilted in favour of women and in addition, the media whip up the passion of "emancipation".
In this crossfire, the only hapless creature that get stuck is the man who has to pacify both his mother and his wife. Two male members have no ego .Have you ever listened to the story of tussle between Son-in-law and father -in-law/brother-in-law.