I have been going through the exact situation with my bestfriend of over 10 years. She's also married with a 3 year old child and another one on the way.

I've always been the friend that she could call to have someone to lean on but after some time I could only hear so much of it especially when time after time no matter how much she saids she doesn't want to put up with it anymore, she some hows give the marriage another chance.

I was just as upset like how you are with your sister but now I've realized that all I could ever do for her is to simply listen.

There are some people out there who knows exactly what is that they need to do and have been given the best advices possible but what they need the most is to simply be heard and understood.

It is hard to stand by someone you love so much settle for less and hoping for something that might not even be available but instead of judging them, you could simply be there for them by listening to them.

Their mind is so clutter of all the things they should do for the family and children and that is when they lose their own voice so by listening to them and allowing them to be heard will help them to finally hear their own voice and strength.

You must try to have paitent and and love and care from a distance. It took me alot of time to accept this.