I may get some flax from you for this but it is obvious you are very sure of yourself she is bi polar. I would let a dr. determine this and definitely not say this to her unless they determine it together. She may just be dealing with depression. If you exagerate it she will start to act bi polar. No one wants to be depressed nor bi-polar. It is a condition brought on by low self esteme. By making them feel like it is their problem it creates all kinds of guilt in them. One thing I noticed is you said she didn't work and you using engineer as a forum name lets me think you have a career and she doesn't. Careers do alot for your self esteme and if she has non it could be she feels inferior to you. The affair could be her way of lashing out at the fact she isn't proud of herself. I am not saying she should go out and get a career but have you mentioned what she does right in her life? Is shes a good mother, does she maintain the household while you work? Do you remind her what she does right and how much you appreiciate it. Finding something she feels good about and reminding her that you believe she does great at it will go a long way to dispelling her episodes of high and lows. If not help her find something she is good at. Give her time. Again, don't diagnose her without letting a dr. discuss it with her. You will only set her off. And by no means having an emotional illness is not a sentance for life. Many people live successfully with one. It is up to the individuals to determine the new level of success expected. I am not saying that they can maintain a normal life but many who have illnesses, (diabeties, autism, arthritis, etc.) learn to accept their illnesses and accomodate for them in ways to achieve some success in life. Just think about it. Do you believe their is a perfect wife for you out there then go for it, if you believe you can manage to love a person who isn't perfect but accept them and try to make life successful by learning to work through the tough times. I have to admit, I wonder if I am bipolar at times but I really believe there will be a new disease that they invent that is between depression and bi polar that covers what I am hearing lots of women experience at our age. Another possible issue is midlife, premetapause, don't rush to conclusions.