"I went out bicycling one afternoon, and suddenly, as I was riding along a country road, I realised that I no longer loved Alys. I had had no idea until this moment that my love for her was even lessening. The problem presented by this discovery was very grave. We had lived ever since our marriage in the closest possible intimacy. We always shared a bed, and neither of us ever had a separate dressing-room. We talked over together everything that ever happened to either of us. She was five years older than I was, and I had been accustomed to regarding her as far more practical and far more full of worldly wisdom than myself, so that in many matters of daily life I left the initiative to her. I knew that she was still devoted to me. I had no wish to be unkind, but I believed in those days (what experience has taught me to think possibly open to doubt) that in intimate relations one should speak the truth. I did not see in any case how I could for any length of time successfully pretend to love her when I did not. I had no longer any instinctive impulse towards sex relations with her, and this alone would have been an insuperable barrier to concealment of my feelings. At this crisis my father's priggery came out in me, and I began to justify myself with moral criticisms of Alys. I did not at once tell her that I no longer loved her, but of course she perceived that something was amiss. She retired to a rest-cure for some months, and when she emerged from it I told her that I no longer wished to share a room, and in the end I confessed that my love was dead. I justified this attitude to her, as well as to myself, by criticisms of her character."
January 1, 1970
https://en.wikiquote.org/wiki/The_Autobiography_of_Bertrand_Russell