I think that depends on the game.And thats what i mean, i love to have Gameplay, but no matter how fun the rpg/sidescroller/vn can be on its own, it always feels disconnected from the Sex part.
If a game is focused on the sex and has a very silly tone and just a sexfest then I can see how any nonsexual gameplay and events can feel disconnected.
On a game where the story(and gameplay) is as much the focus as the sex is, then the gameplay does not feel disconnect as it is expected and follow the natural flow of the game.
The type of games out there varies a lot. It all depends on how they are executed.