Often times the behavior is another form of addiction. Not justifying it by any means because my sister is classic for this. In fact, they just had the car, boat, camper and almost the house taken back due to lack of managing money. I'm certainly no angel but if I get over my head for poor planning, I pay the price..... I don't ask for money or anything. Anyway, my Mom bailed them out to save the house last week. Everything else is gone. She gave them $4000 ( money she doesn't have since she's going through a divorce herself ), but I finally said something 'cause this isn't the first time. It's supposed to be a "loan". I told her that she should have given them the money on the condition that they save the house only to be sold and repay you when sold. They can't afford this house. They live in a home they built, over 2500 sq. ft. and no kids. Way more than they need. I have a family of 5 and live in a much smaller home. But my Mom swears she did the right thing. My sister is almost 45 and this is not the first time they've been bailed out.
A long time ago I cut those ties with my sister. We talk, but we are not close because she pulled that stuff on me a long time ago and when I wouldn't help her out anymore, I became the bad guy.
If a relationship is one sided, and causes you stress, be it emotional or financial, then it may be time to sever them. JMO.