Adult readers can always skip a passage they find offensive or, in extreme cases, stop reading the book altogether. Much the same goes, I believe, for the question of sexuality. It has to be up to individual writers to write what they have to write for the readership they wish to reach. No one is forced to read a novel, just as no one is forced to sit watching something they dislike on television. We all have the ability to make a choice.
Most readers are more than capable of exercising that choice.
Reading requires effort and the exercise of imagination, in a way that watching a film does not. That's why I do believe that films should be censored, but not novels. Anyone capable of making the effort necessary to engage with characters on the page ought to be able to deal with his or her own feelings about those characters and what happens to them. The minority who cannot or will not are unlikely to be motivated only by what they read. Reading is a much more interactive business than watching film, and because of that, it is also much more satisfying to those accustomed to it.