Spicing things up (mostly futa/m)

Here's my first attempt at writing & sharing a story here. I know I'm not the best writer, but hopefully you'll enjoy it. As you'll see, it takes me awhile to get things going! It also takes me forever to write, but the process is kinda fun. Anyway, have a look at what I've finished so far which really just starts to get to the good stuff. I have many ideas for how I might continue the story, but let me know what you think. Any constructive feedback will be appreciated. (It doesn't all have to be positive so long as its constructive).

It's mainly intended to be a futa/male sort of story (as you'll see), but with some other things may get mixed in depending on how (if) it evolves.

My sex life with my wife Kendra had been going downhill for awhile. She still looked great, with a trim, athletic body, long firm legs that looked amazing when she wore her favorite high heels, and an utterly perfect pair of breasts. I was the envy of my friends for having a young and beautiful wife, but only because they didn't know that she was never in the mood in the bedroom anymore and the rare times that we did have sex were nowhere near as they good as they had been when we first got together. So, when a spam-like email offering a free sample of a product "110% guaranteed to spice up your sex life!" made its way to my inbox, I didn't delete it immediately. The ad didn't offer any real specifics about the trial-sized combo pack of "14x25B for Her and AVx25 for Him" other than that they were some sort of pills that would "take things to a whole new level in the bedroom!", "flip your sex world upside down!", and "keep you and your partner in bed for DAYS AT A TIME!" Surprisingly, the ad didn't ask for a credit card or bank account number and had no mention of Nigerian royalty, so I figured "why not" and sent in a request for the free sample, copying my wife on the request with a note saying "What the hell. We don't have anything planned for next weekend, do we? :)" I figured she'd take a quick look at the ad, maybe have a laugh, and that would be the end of it. To my surprise, she replied a few minutes later with an IM saying "LOL. We haven't tried anything upside down in a long time. Can't make things much worse than they have been, can it?" Not quite what I was hoping to hear, but there was a hint of promise in there.

A few days later, a large envelope arrived in our mail from "Futransformicon Enterprises." Inside were two separate packets, each containing a single, rather large capsule. The "14x25B For Her xxxtreme pleasure" packet contained a pink pill, and the "AVx25 for Him" packet contained a blue pill. The packets didn't seem to have any more info, other than some silly messages like "You've never cum like THIS before!" on the pink one and "New and improved formula - Now you can keep up with her!" on the blue one. Also inside the envelope was an order form which listed the pills we had received plus a whole bunch more in both the "For