I placed it in the pool because I thought it was interesting wondering what the scene is about with the man's tired/lost look on his face and the more happy girl reaching around to comfort him. To me, it could be interpreted in a number of ways. Is it someone consoling her lover? Is it a seductress who has what she wants in her clutches? Is he downtrodden or under a trance of sorts? What is their actual relationship (if any)? What happened to him that led to his demeanor? It's not your "typical-looking" image, it is apparently a standalone one, and the artist never gives much detail about it beyond its given visuals. By design or not is unknown, I know it is not your typical "Speculation Fuel" picture, either, but I also felt it fit well within the guidelines of the pool (though I can understand if anyone disagrees).
I can buy it. There does seem to be a sort of ambiguity to the guy's face here, far more than you'd think should be if a guy found himself in this situation. In fact I'd even go as far as to suggest he looks downright unhappy about having a sexy nude woman pawing him up in the shower, a scenario I think most dudes would rate at least a 7 or 8 (out of 10) on the fantasy meter.
There's nothing in the image to substantiate this, she's not even slightly transparent or anything, but I almost get the feeling from this that the girl isn't even "really" there, she only exists in the guy's mind or something... almost like she's the ghost of a dead/former lover still lingering. Again I can find nothing in the image itself to support such a conclusion, but the atmosphere seems to be there. Personally (and I'm no judge of these things really) I think it's just fine for speculation, even if the "speculation" is a tad more mundane than usual for this pool.
That shouldn't be in "Speculation Fuel" just for that. Maybe in "Food for Thought" or something similar, but not Speculation Fuel. Otherwise you can just overthink every picture and put all of Danbooru in that pool.