Taking forever to get to the sex. First, it's a peek through the keyhole to see them nekkid! Second, after waiting forever, we get to kiss! Third, if they want to really draw it out, a French kiss will be next after waiting another eternity. Fourth, after another eon, the main character gets a handjob. Fifth, after yet more waiting, it's now a blowjob! Sixth, after another millennia, they're all hot and bothered, but only strip down to their underwear before getting cold feet. Sixth, same thing, but this time they're naked now! Seventh, a hundred thousand years later, the girl is finally comfortable enough to be eaten out, but her feet get cold once again the moment the cock tip touches her pussy. Eighth, and finally, at the dawn of the final day of time itself, the sex scene finally happens.
All of this frustration gets compounded when it's a harem game--doubly so when there aren't any/many more sex scenes afterward.