@adamstan Personally I think that 18+ content must be in a game which is only about relationships and romance. But when the story is about MC trying to figure out who he is, trying to escape the depression, finding reasons to life etc( I'm referring to Everlasting Summer, the novel you probably have never heard about) by being in romantic relationship and making friends, then this porn stuff definitely even isn't supposed to be considered as an addition to the plot. Same goes about thrillers, detective stories and so on. But for the sake of honesty I have to mention that I haven't read a novel similar to which I wrote earlier about so far(and maybe will never read), so you can just forget about it xD.
For me, 18+ stuff should be a cherry on the top of the cake, not of the steak(that thing were the first that came to my mind, dunno why)