I mean, inasmuch as a given game has a story, then character death in a game's story isn't really much different from character death in other media. The difference is whether or not the player feels like they should've been able to do something about it. I mean, one of the basic features of any video game is interactivity. In the context of your story, if the character is killed because the PCs were lazy, stupid, or made some egregious error, then the player's probably going to be more annoyed than anything else--they'll say "I should've been able to keep that from happening." Unless it ends up being some kind of critical developing moment for the characters involved ("I fucked up and got Ted killed can't let that happen again"), you're probably just disappointing the player for no reason. It kinda has to do with the expectation of the players. If your characters are in a war zone or a bloody ghost house and no one is ever killed, it might feel stupid after a while.
It really is a question of player expectations. Sure, the shock value is far, far higher if a character dies in the middle of your slice-of-life game, but I dunno if players are going to be too happy with it. It kinda has to be planned pretty carefully. I dunno if a porn game's really the best environment for it. Then again, I'm more of a "characters" than a "plot" person when it comes to porn games, so maybe I'm not the best one to give an opinion.
(I think it was Agatha Christie who said "murder your darlings," but then again she wrote mysteries involving murder. I think her advice was just to not get so attached to your characters that you can't sacrifice them in order to tell the story that you want to tell. In a regular old novel or even novel series, I'll gladly say that the overall story is larger than the characters. In a game... well, I dunno.)