Why don't you like your sister-inlaw?
What happened?
To be blunt she is an idiot.
To put in nicely she is very inconsiderate of the rest of the family. She is very nosy, has to know everything about everyone. She forgets to informs us of stuff and then acts like she did. She is always late even when you tell her it's a certain time or don't show up, she will show up late. She says one thing then do another.
I can go on but you get the point. I do not admire anyone that is like that.