Thank you @Former-Member, @Bunniekins, @Faith-and-Hope and @Former-Member.
Really appreciate the feedback. My brother and I have been talking about this a lot and also thought that she needs to want to be treated, otherwise there's nothing we can do about it. But seeing her like this is really hard.
@Bunniekins, she is not married. She used to work full time before resigning and decided to follow her dream and change career. After she completed the training, she didn't get a job right away and turned down some opportunities. She then wanted to work with my dad and now causing so many issues within the company. She feels that no one in the family cares about her and her well being. Every night she locks herself in the room and sometime starves herself. I think she now has decided to leave the company because it didn't work out as she expected it to be and maybe go back to pursue that other dream again. She has done this a lot as a way of "escaping".
@Faith-and-Hope, just had a read about personality disorder and that is definitely her. I also think she has bipolar because at times, she could be very nice and normal. It normally lasts for a day or less before she turns 180°.
When she is nice, she's really (almost too much) nice. And she gets disappointed when people don't reciprocate when she expected something rather unreasonable from them.
Like I said before, for some people, she has a great life, she travels a lot, she used to have lots of friends (before isolating them all out of her life), she has my parents as her safety net. I am very worried about my mum too, because she doesn't know how to deal with my sister and her emotions gets dragged around by my sister's behavior. My mother is doing the total opposite of what your suggestion: she always asks us to bend over backwards for my sister, even though we have told her many times that it is not healthy.
@Former-Member, I'm sorry to hear about your brother.
I used to spend a lot of time with her and now she's like a stranger. Especially since I got married. She probably thinks that I've betrayed her. My husband and I try to see her every weekend when she's in town. If we're lucky, she'd get out of the room and chat with us. Otherwise she'd stay in her room. She also has told me that she has a personality clash with my husband, which of course is all in her head because they never have any confrontation or argument. She also feels the same way towards my brother's wife.
I would love to go to the GP with her, but I wouldn't even know how to initiate the conversation. I worry that she'd be defensive and verbally aggresive if I float the idea.
She was violent towards my brother once out of nowhere. I don't think she'd do the same to me, but I just don't know.
Again, I really appreciate your feedback. Even just talking it out like this helps. I always wonder if I stuck around her and not getting married, would she be in a different place....?