It's a well written story. :-)
Here is some things I noticed though..
"...ignore the collar and leave it where it lies.."
I think that sentence is better with the word "it" in it, there wasn't any in the original post.
"Her bottom and stung remembering the belt,..."
I think the word "and" is misplaced in that sentence and that it's better without it and also that you've mixed up the two protagonists in that sentence when proofreading not noticing that the sentence don't make sense with the word "he" at that place.
"...and crawled up into the bed to straddle her and replace..."
It's just a suggesting, but what about adding "into"?
"The pleasure and pain intertwining to build a release so intense it threatens to overwhelm her."
I might be wrong but I think you meant "The" here and not "He".
Other then that I can't notice anything..
Ps.. I'm not a native english speaker so I don't actually know for sure what is right or wrong but I hope those things might improve the story a little.
Other then that, thanks for a really nice story :-)