"It is what you read when you don't have to that determines what you will be when you can't help it." - Oscar Wilde
Well, this was akward. I have absolutely no problem with sex scenes fading to black, especially when the plot is strong and I get engrossed in a mystery. On the contrary, I prefer my mysteries without copious amounts of smut mixed in. BUT. This one felt... odd. Why would you describe the foreplay in detail and end the scene with one MC being impatient and thinking how he can't wait for... things to happen? He can't wait to feel it. And then fast-forward to the next couple of DAYS? It's like telling me he's having the best burgers in town, but not elaborating on what they actually taste like right when he takes the first bite! If you want your sex scenes fading to black without frustrating your readers, doing it by going into detail right until the big finale is probably not the best way to do it. Just keep it vague all around!