This concept is not new. Taoists in China have have taught semen retention for centuries. There are different versions. One where the man ejaculates infrequently (21 days to 3-6 months), or a different version where he never comes or never gets close to the edge. The later version also can involve a woman, and she never gets close to the edge either. They tout it as a more spiritual way of love making. My goal is to make sure Mistress has as many orgasms as possible so we won't be practicing that one.
Most of the info I found was a non-kinky variety, which adds credibility for me. As I have practiced orgasm denial for many years, I was surprised how much of what I get out of it, is what non-kink people get out of it. The thing that surprised me the most was the amount of sleep one needs. After long periods of orgasm denial I can't sleep a full night. I thought that was a bad thing. It turns out, one of the supposed benefits of not cumming is actually needing less sleep due to increased energy.
As I said, I have enjoyed orgasm denial for some time. However D/s is a big part of my sexuality. To make orgasm denial more D/s oriented, wearing a chastity device fits the bill. Being unlocked for only one purpose (to pleasure my Mistress) makes me feel even more submissive.
The most exciting part of this is the possibility of having orgasms without cumming. I remember when I was a kid and learning about my body. I learned to masturbate before I was old enough to ejaculate. I could go forever. When I had my first orgasm, I was excited because I was becoming mature, but I was also bummed that I had to stop masturbating as soon as I came. Recently Mistress had me tied to the bed. She had me on the edge and was using the Hitachi on the area between my balls and butt. She managed to keep me from cumming and looking back I was likely having orgasms. It was incredibly intense and if I can learn to do that while we are having sex, I will be a very lucky man.
To conclude, semen retention is something I really want to explore. Semen retention doesn't mean we are not having sex. If anything it means we are having lots of sex whether it be intercourse, oral sex, or masturbation. To train me to be able to have sex, have orgasms and not ejaculate would be a huge win for us as a couple. Even if we don't get to the point of me having ejaculation free orgasms, I can see no benefit for us as a couple for me to ejaculate more than a handful of times a year.