Hi,
I'm sure dev will appreciate your warm words regarding his game, let me thank you on his behalf.
Regarding the sex issue - you need to unlock the "dick" interaction, which is 20k dex upgrade (dex lvl 4 or 5)
To address this and many other questions and issues regarding the game, we've created a dedicated Wiki page, where you'll find exact info regarding all the upgrades and other stuff (it's still a WIP, but it already has many information - give it a read, its worth it!)
Cheers