"... but I do deny them my essence."

So he basically never has orgasms. That explains a lot actually.

He seemed to be pretty out of his mind the whole time.

It's funny but I never imagined Ripper wasn't able to orgasm, but rather couldn't even get it up just because he was getting old. (Granted, I guess you can't have one without the other but still)

Ripper mentions he first noticed it after lovemaking, so perhaps it just wasn't as satisfying anymore? In any case, it was almost certainly because he was getting old, which happens to everybody. If you look at it that way, it really helps explain some of Ripper's actions in the movie.

Getting old is something that nobody can change, and it will happen with 100% certainty to everyone, so in that sense everyone is "doomed." When Ripper launches Wing Attack Plan R, he does so knowing that there is a 100% the bombers won't be recalled, and that if the U.S. doesn't back his plan then there is a 100% chance the entire world will be destroyed. And Ripper accepts this fact just about the same as any other man would simply accept growing old.

The only difference is their situation. A normal guy with a wife and family and a steady job might try pills or just move on with life. But Ripper's been in the service for so long staring at the Red Button with an enemy holding the exact Red Button of their own. Not to mention a regular guy's probably surrounding by similar people whereas Ripper probably has been hanging around with warhawks and conspiracists for years; after all he passed Gen. Turgidson's screening test and Turgidson even tries to defend Ripper at first, so who knows how many like-minded individuals Ripper's been hanging around with for several years.

Not only that but if Ripper really did believe in the conspiracy theory then the big factor is he actually has the nukes and Wing Attack Plan R to try and "fix" the world as he sees it. Imagine how many conspiracy theorists would probably try to carry out a similar attack if you took them out of their trailer or basement/bunker and suddenly gave them the means to act out their fantasies.

Then there's the possibility that the whole Communist plot necessitating Wing Attack Plan R was just BS by Ripper and that he never really believed any of it, but was simply suicidal enough over not being able to have sex that he decided to take the rest of the world with him (which I wouldn't rule out either).

Can't be too careful with all those weirdos running around.

Ripper was batsh!t crazy from the git=go

He reminds me of the general from Paths of Glory. Both are shown as being normal in their opening scenes, maybe even good men, before it's revealed that they're both batshìt insane.

He didn't think it was the Commies who gave his the "profound sense of fatigue"; he interpreted it to a "loss of essence" because he had lost some "precious bodily fluid" inside the woman he was with.

When he later states that he does not avoid women, it could mean that he pulls out before things go off and just keeps it that way, or that he pulls out and lets things go off outside of whichever woman he is with.