The retention thing is really good :D I've been doing that, somewhat, for years. Dunno how to talk about it really... But like, "spreading out" intimate times with my wife over days or weeks, i.e. we have sex but I don't orgasm/ejaculate, until one day I do... It makes things quite magical. It feels like, hmm...generating power between us. After each time when I haven't done that, I feel very calm and energised and she seems very calm and expansive, I feel so much love for her, and this builds up over days.. I don't mean that I normally don't feel love for her, but this kind of loving feeling that starts developing feels more...conscious?
Anyways. The reason why I started doing that was, I remember finding out as a young man that at times when I was very aroused, and it felt very important..then after ejaculating I would *immediately* lose all interest and arousal, as if those feelings had been turned off with a switch. It made it obvious that those feelings were purely generated in my body, not my mind. I accepted that obviously, but thought it was weird and didn't like it. Very strange feeling, to have something seem super important and then next minute, you've stopped caring about it at all! So years later with my wife, this same thing would happen (though actually the "instant off" thing has decreased over the years) and I really didn't like that, so I tried just not ejaculating to see what would happen...