What causes your prostate orgasm to finish?

Sometimes pure exhaustion.

The fantastic thing about POs is that you can keep getting them again and again.  I (saddly) am out of practice now and have to re-learn how to get them but previously I would just get one after another and would finally have to stop from sheer exhaustion.

I put down "other" because generally nowadays I can achieve a prostate orgasm (PO) mostly in bed many nights through diddling my nipples. I am grateful for the many benefits that Aneros has brought into my life over the years.

After a journey of 4/5 years with regular Aneros sessions, I achieved a big breakthrough in mid September 2016 with Super-O's and MMO's. That is when I began serious diddling of my nipples most nights and began to achieve prostate orgasms mostly in bed many nights.

I can have prostate orgasms singly or one after another (mostly three to four in succession). The pleasure is awesome!

I think they just sort of fizzle out.  I say this with the caveat that I have had prostate orgasms before with other toys but not necessarily Aneros, if I have they're just in the Mini-O category.  But usually they are starting to ramp up toward something and then plateau; at some point my mind takes me out of it enough to know that it's ramping down and I either try some manual penis stimulation (edging...with varying degrees of success) or I accept the inevitable and pull the Aneros out.  Either way I'm not ready for it to end usually and a bit frustrated a lot of the time.  Sometimes it ends with me ejaculating but I try to control myself. 

looks interesting 

Usually I'm wore tried with the muscle contractions and by this time I've had  near a dozen Super Os with plenty of P waves and milked an ounce of pre fluid and possibly had a few or more wet ejaculations hands free or by cheating. Sometimes only one firm press on the base is enough for wet O. Usually the second wet O just flows out without contractions like the first. The third is just shear insanity with full on cheating 

Usually from exhaustion.

Mine only finish when I decide to end them - otherwise they can go for hours with building intensity and multiple Os and SOs. Someone I finish with an explosive TO and a SO simultaneously - if you haven’t experienced that, it’s the ultimate in pleasure and will leave you exhausted but wanting more!