Steve seeks out every sweet spot he can think of, brings Bucky to edge of orgasm, backs off, does it again, backs off. He does this until Bucky's hair is sticking to his damp face and he's giving these helpless little moans. Steve's ecstatic. He says that's so hot, keep making those noises, you're beautiful. When Bucky is already gone when he wakes up the next morning, Steve only feels a little disappointed. But later... when Bucky's been avoiding him for three days, then four, then five... Steve knows he fucked up and has no idea how.