Is this official? Did Rider and Sakura really have a threesome with shirou in fate/hollow? Really?

Yes I think this is from hollow/ataraxia h scene

to someguy379:
Please refrain from posting spoilers next time. Thanks.

shirou finally does it with rider, hmm don't know if I should be happy for him or stab him with a feather.

He doesn't actually have sex with Rider or Sakura. It's a dream that Rider gave him using her magic. Originally she claims it's to help Sakura's chances with Shirou, but Shirou turns it around on her and reveals that she is also attracted to Shirou (and apparently has no problem sharing him with Sakura).

Well, he has sex with Sakura in a different scene, and if Rider is giving him a "dream" it's likely that she is actually having sex with him during that time, like in HF.

Each of the Eclipse sex scenes in Ataraxia take place in UBW True End (Rin's), UBW Good End (Saber's), & HF True End (Sakura & Rider's).

The thing about Rider is that despite the fact she really does try to support Sakura hard on getting Shirou, she herself is also attracted to him.

However, Rider feels if she makes a move on Shirou as well, that he would drop Sakura and go for Rider.

So she really wants to fuck Shirou but at the same time wants to help Sakura regarding Shirou as well.