This has been a great thread, and I'm glad that I could share your personal lives. But it's been a while since anyone posted, so let me tell mine, and hopefully we can revive this thread.
Twenty years is a long time, even for the most happiest of partners. I was on the way to accomplishing the Jack-Ennis thing, but sadly....
I met Tom in a public place in 1972 and invited him to my house. An intense relationship developed almost immediately, and we saw each other 3-4 night a week for about 2 months. He was an Air Force Reservist, and prone to often and long trips away from home. We never committed to each other exclusively, so I could not feel hurt when he came back to town and told of other men he had met; of course, I was doing the same, but I still loved Tom and he said he loved me. In 1976 he was reassigned to San Antonio, TX; Houston was close enought, so I requested a transfer with my company. That was a disaster...every time I called to arrange a weekend, he was gone, and when he called me, I was not available. But in a 3-year period we did manage 4 or 5 visits. In 1979 he moved to Washington, D.C. and withing 3 months called and asked me to come visit as he would be going to Spain for an indefinite period. I did, and lived in his house for several months (I got a job so I wasn't sponging). When he came back, I had already moved to my own apartment, and we saw each other often, when to dinner, dancing at the bars, social gatherings with his friends (mine were never good enough for him). Finally in 1983 he disappeared. I knew he had to fly to Spain on an air-evacuation job, but I never heard from him again. When I called his parents they acted like they didn't know me (I knew they hated me) and would not give any info. Several weeks later I ran into a very close friend of Tom and he told me there had been a plane crash with no survivors. I mourned his death as a friend would, not as a lover, moved back to California and went on with my life. I remember him on certain occasiones, or when my mind wanders back to other times, but never with profound sadness because he was a friend of mine, and I believe he would have wanted it no other way.
As for an answer to the original question...I don't think I could have gone on with it very much longer. It was a frustrating situation, demanding of time and energy, and in the end, not the satisfaction I would have wanted. Had he lived, things might have been different, but that's something I could not have know.