Mind you, now I'm imagining a scenario where this hits right at the start of a sexual relationship--post-WS, they hook up, or start to, but Bucky flashes back to being raped by a woman, it's awful, Nat backs off and is trying to comfort him--but before they have a chance to try again they figure out that that was Natasha's mom and EVERYTHING IS RUINED FOREVER?

...Maybe no incest then.