I'm looking for manga where a male protagonist is about to discover sex and experiments with (a) girl(s). I prefer them to be a non-romantical interest as he doesn't have an interest in romance and thinks romance can wait for later when he's a grown up adult that's working.

I don't want him to be a manwhore though.

Nana to Kaoru I'm not so sure about it but I like to think the main male lead is completely satisfied with their BDSM-relationship...
TWGOK might fit, it's less about the physical part of relationships though - The main male lead (who is only interested in 2D girls) has to seduce real life girls using his knowledge aquired through games. I haven't read up to the latest chapters though...