Not bad.

Not bad at all

Not bad? This was great!!

That was a good story.

I will be honest
I liked the sfw parts with RD and FS interreacting and I believe if you made it only about that, so like fluffy short romance story it would be better than mixing it with NSFW parts that in my mind weren't exactly executed that well. Or maybe I'm just biased since I don't like the specific fetish described in the story.
Also explaining how well known characters look like (I'm refering to the beggining of the story) is really unnecessary and makes it worse.
Over all I think you got downvoted too much, there are much worse stories with better rating so I guess you just got unlucky with the audience xd

I f*cking love flutterdash! The pacing was solid throughout the story, and I absolutely loved hearing both of their thoughts as they share their time in the gym. Yeah flanks are great -right up my alley, but I also loved the cute buildup. Great work!!