Hubby stressing me

So here's the issue we have sex I'm enjoying it loving that it feels great so then he's about to cum and I'm ok with that because when he does I usually do as well but he want to go longer so he slows down but the only problem with that is he can't maintain an erection some times so them neither one of us gets to finish cause then he feels bad and beats himself up cause of the loss of the erection but I keep telling to STOP FREAKING DOING THAT  and  but yet he keeps freaking doing it I'm more of let's get to the point kind of person. Then when he gets it up again I'm no longer wet so then he thinks I'm not turned on by him but yet again I explain I was and am turned on by you but this stop and start shit has to stop like I don't know what else to do