Whatever the reason is, Over 90% of the wife have the same feeling like 奶奶唔適合湊孫 or not willing to live with 奶奶...etc...
奶奶 and wife always have dispute.... This is the nature of human ...I think nowadays, those 奶奶 also know about this as they also had been 媳婦 and argued with their 奶奶 before....