He's right. Tren and deca certainly aren't the only steroids that can lead to increased levels of prolactin.
That said, Bonez also had it right earlier in the thread. It's very hard to pinpoint the cause of these things, particularly without even getting bloodwork done (E2, PRL for starters, maybe T3 though personally I've never found my T3 to be off, even in the midst of some pretty ridiculous tren cycles, but I suppose we're all different).
For example, it could be virtually the complete opposite of what you imagine. Steroids such as plain old testosterone can bump up dopamine levels. This elevated dopamine can lower norepi levels. NE is normally a trigger for orgasm...so lowered NE means more difficulty finishing. So if this happens to be the case, caber sure isn't going to help. (Btw, mucuna pruriens, which you also mentioned, is good stuff, generally speaking. Like caber, it won't help if your dopamine happens to be high already, but if you get a good preparation you'll definitely reap its benefits in other situations.)
Good luck. It's a bummer for sure; I've definitely had times when sex lasted far longer than necessary while on cycle. It's all good up to a point, but then it's just a pain in the ass.