Falling asleep with my cock in her ass M20s/F20s

I've written about this with a different throwaway account, but it feels so awesome I wanted to share it again. Mods, feel free to trash this if that breaks the rules.
We've been married a couple of decades (the M20s/F20s tag is for when we started doing this). So this isn't a new story, but it's one that gets repeated frequently.
She's a super sound sleeper and gets a little annoyed if I wake her up for morning sex. But she does enjoy anal (it was actually the first type of sex we ever had) so with a little coaxing I can usually wake her up around 4-5AM and get her to go prep herself. A couple of minutes later, she'll groggily stumble back into bed and hand me the bottle of lube.
A little foreplay with fingers and such, and she'll give "the moan" that's her signal for "put it inside me, now!" I'll scoot myself forward a bit, put the head of my cock up against her hole, and apply pressure until the ring of muscle opens and engulfs me.
At this point, I'll usually be too horny to resist fucking her ass. But I've never been able to last very long with morningwood, so it'll only be a few minutes before I unload inside her.
Like most guys, the end of the orgasm is when I stop being horny. Dunno why this happens, but it does. But she HATES it when I pull out right after fucking, anal or otherwise. So the only thing to do is grit my teeth and push in a little deeper. Eventually, the post-cum sensitivity goes away and it's sheer bliss just resting there with her ass gripping my deflating cock.
With regular vaginal sex, I'll eventually just slip out when I go limp. But with anal, there's the tight sphincter muscle holding me in.
And at this point, she'll sigh, press her ass back up against me, and wrap her legs around my top leg to hold me in place. And then seconds later, she'll be in a deep sleep. Being a dude, and having just filled my favorite oriface with cum, I'll slide down into a post orgasmic coma.
I can't stay asleep in that position, though. I'll wake every fifteen minutes or so, realize that her ass is snugly gripping my cock, think about how awesome that feels, and then drift away again. Sometimes, her ass does this involuntary "grip-and-release" thing where it tightens up almost to the point of painful compression and then completely relaxes again. This can be repeated dozens of times either slowly or sometimes in rapid succession about the same speed as a nurse inflating a BP cuff. She has no idea she does it because it only happens when she's deeply asleep.
Eventually, the alarm clock will interrupt our bliss. Time to wake up. But sometimes you just gatta hit snooze and fuck that ass one more time before getting ready for work.

Source: reddit.com/r/gonewildstories/comments/3rt6wm/falling_asleep_with_my_cock_in_her_ass_m20sf20s