We have two women who are keeping themselves in relationships where their men let other people run their lives. The girl who has the boyfriend needs to cut her losses. It doesn't matter whether he is too close to his sister or not or whether anyone else thinks this is wrong or right. What matters is that you find someone who is willing to have a relationship with you where the two of you work it out and nobody else can interfere. There is advice and there is someone else calling the shots.
For the woman who is married, you need to make your move quickly. Practice double the birth control you are on now so you don't get trapped in this relationship. I married a man extremely close to his parents but he was willing to actually move in with me so we could be a couple. We lived nearby until they passed away but had independent lives. It's going to take a lot of therapy to get your husband to this point. Even if he does move away from home, you need to make sure that you can have the kind of relationship you want to live with the rest of your life. Mil's can control from afar...if the husband lets her. You have to see what he is depending on her and his dad for and make sure that is what you wish to have happen for the next 50 or so years.