It's been for me about 6 or so years that my wife and I have been practicing Karezza and I have some thoughts I want to share with you.
I have been glorying in approaching the limits and feeling exquisite whole body pleasure in more of an active high energy form of Karezza.
On the spectrum of let's say left/right, with left being stillness and just connection, and right being out-and-out sex almost to orgasm but not quite, I am more on the right side.
But I find that doing things this way leads to a cycle where my erections become all of a sudden really bad, and only coming will resolve that and reset the cycle. Coming isn't really that great. It's just that the ejaculation will reset things, so I ejaculate by choice. I don't seem to have negative fallout from this either.
I've talked to other guys who have had the same experience. I think it amounts to a lot of edgy sex creates high amounts of hormones that eventually kill erections. I'm not sure if it's prolactin, vasopressin, or estradiol, but it's very real and ejaculation resets it.
I also find that if I don't get so "edgy", if I stay a bit more toward the center, this doesn't seem to happen. I may come occasionally but it isn't necessary to reset the hormones. This type of coming when it happens does result in mild or strong fallout.
So my question is this, and hopefully you old-timers here still poke around now and then on this site and can answer (or you new folks who have been at Karezza for awhile). Do you men (or your male partners) experience what I am describing?