My SIL (and family) is staying over Christmas and I've always found her really hard to deal with as although she is perfectly nice and friendly, she just does her own thing the whole time and doesn't join in with what the rest of the family is doing. She seems to have very fixed ideas of what she wants to do and when and seems to find it difficult to compromise/fit in with what everyone else is doing.
For example, we might all discuss the day before going for a walk at a certain time the next day (to fit around kids) and when it gets to that time she doesn't come because she is in the middle of some other task that she refuses to stop until she's finished. Or on Christmas day when we're all enjoying a champagne brunch she doesn't join in because she's folding up wrapping paper or something in another room.
I don't think she's deliberately avoiding us (we all get on well, no major issues ever) or being rude, I think she just finds it very difficult to "fit in" with people around her and the importance of whatever task she is doing just overwhelms everything else to her.
I would really like to be able to understand her a bit better and to imnprove our relatiobship. So I was wondering if anyone else is like this and can explain what drives them/why they find it hard to accomodate other people's plans?