Never the 'Twain Shall Meet?
I would try to bear in mind that it was a good sign that she was willing to express her feelings to me openly -- a sign both that she cared enough about the relationship to try to protect it from being changed in a way that would make her unhappy and that she had confidence in my willingness to listen to her even when she was expressing criticism or distaste. I would also note the fact that she was not asking me to stop seeing my friends, merely describing her unwillingness to participate in plans that involved them.
All these points notwithstanding, I would not immediately agree. I would ask her to elaborate on her request. I would try to understand the events and feelings that precipitated it. Maybe this request was more of a way of articulating a strong feeling than a literal and well-considered policy about her future intentions. It does seem rather drastic, after all, in most scenarios, to say that one will 'never' spend time with certain individuals again, especially if they are close with one?s significant other. If after discussion her position seemed baffling to me, but I felt that it was a fundamentally fair or valid subjective judgment, I would probably accede to her request. However, since I recognize that people change over time, and that this fact applies both to my partner and to my friends, I would broach the topic periodically. I would mention news about my friends and describe time I spent with them and gauge her reaction. I would try to make the topic seem non-threatening and open for discussion. At some point I might express the feeling that I would feel closer to her if I didn't have to keep such an important part of my life totally cordoned off from her and my relationship.
On the other hand, if after initial discussion I not only felt baffled by her reaction but felt that she was being unfair and mean-spirited, I might reevaluate how important this relationship was to me and weigh that judgment against my attachment to my friends. If this process left my friends looking better and my relationship looking worse, I would try to convey gently but clearly that I was bothered by her reaction and that my friendships were important to me. If she continued to react badly to my perspective, I would probably pull away, either ending the relationship or really insisting on my space to live my life on my own terms, including spending more time with my friends and other commitments, and less time with her than I previously had. She would then have the choice to adapt to my needs and reevaluate her attitudes or to decide that being with me wasn't worthwhile to her.
In all cases, dialogue and honesty seem integral to a good handling of the situation, and respect for one's own needs and feelings and those of one's partner. Walking this tightrope sometimes calls for a delicate balancing act. But relationships are like that, sometimes. Negotiating these conflicts well strengthens the bond between partners. Ending a relationship with an incompatible person also clarifies our self-perceptions and helps us identify the right person next time.