demora

It sounds to me like the ultimatum needs to go out to the sister and her bf. Your wife shouldn't have to chose, but her sister needs to take responsibility for her life, as does her bf. The hard part is going to be getting your wife to see that. It's not splitting them up, it's merely encouraging her sister to do something...it doesn't have to be "you have 3 days to get out". Agree on a date, something generous so your wife won't think your goal is throw her sister out on her ear, and she will still feel like she is helping her...something like by the end of the summer, her sister needs to have stable income and be looking for her own place. By say...the end of August, she needs to be moving into her own place.

There is no easy answer and she shouldn't have to chose between the two of you. There is no reason why she can't have both of you in her life, but she needs some perspective on how you feel and reality of what her sister is doing.