A dear and close friend of mine was married about one year ago. Before and since the wedding, my friend has cried to me about the bad behavior of her now-husband. On one occasion, he exhibited some of this bad behavior in my presence, and it was appalling. He overindulges in alcohol, makes advances on other women, and becomes belligerent. In my opinion, he is embarrassing, disgraceful, and unkind. He is not violent, and her physical wellness does not seem to be in jeopardy, but I have expressed my concern to my friend about her emotional well-being in this relationship. She agrees with me.
Nevertheless, my friend recently invited me and my partner to join her and her husband for dinner. The invitation actually immediately followed my friend's latest lamentation about her husband's behavior and the uncertainty of their future. (NB: The last time that my partner and I joined them for dinner, my friend and her husband ended the evening shouting at each other on the sidewalk outside of the restaurant. They both left separately and without saying goodnight to my partner and me.)
What am I to do? I love my friend dearly, and she is choosing to stay in this relationship; does our friendship dictate that I withstand her husband's company at the occasional dinner party? Or do I take a stand and request to her that he and I not share space until his behavior is improved?
Few things test a friendship the way that an Unsuitable Spouse does. The picture you've painted of your friend's Unsuitable Spouse gives the appearance of alcohol abuse, to be sure, and History is littered with the bad behavior of the Overimbibed. Etiquetteer could not help but think of Emma, Lady Hamilton, the most infamous and dazzling adulteress of her generation. While she stayed in Canterbury with relatives of her deceased lover, Lord Nelson, they began to receive invitations superscribed with "but not Lady Hamilton." Her reckless behavior with champagne had ruined what little reputation she had left.*
You want to support your friend without subjecting yourself to the bad behavior of her Unsuitable Spouse - and incidentally, protect your own partner from it, too. The time has come to start declining her invitations for activities that include him. By all means continue to see her on her own. You can emphasize, gently, that you value the time the two of you spend together.
At some point your friend needs to confront herself with the Ann Landers Question: "Are you better off with him or without him?" It's not up to you to pose that question, but since she is already using you as a Sob Sister, you may end up posing it. When she comes to the conclusion that the answer is "Better without him," she will need supportive friends to encourage her to take the next steps. Good luck.
*From Emma, Lady Hamilton, by Flora Fraser, page 271.