I think we can't. Why would we?
Because it's too obvious. If the writers are clever, they will set up future visions, let the audience think one thing (something that seems impossible, to grab our interest) and then turn it 180 on us so that we realize what we were looking at was never so impossible because it was completely different from our assumptions.
Olivia is doing something in her flash-forward that doesn't involve infidelity. The babysitter isn't being drowned. Demitri doesn't die on that day (just because we heard of a report he was murdered doesn't mean it's true - maybe the FBI issues a false report for some strategic reason?)
But I'm assuming these writers are clever.

I've fallen into that trap many times!
Olivia would know the difference and would be very well aware if the feeling she felt was that of love or hate.
Then why didn't see say she was "in love"? That's the kind of thing that signals to me that the writers are going to pull a fast one. They've given themselves a suspicious degree of wiggle room.
What's all this about adult siblings prancing around in their skivvies? It would actually be worse if they were related, since you'd have genetic sexual attraction without the Westermarck effect, since they obviously weren't raised together.
I didn't see them doing anything too salacious.

Okay granted, that's a far fetched scenario. It's fun coming up with zany explanations for this stuff. For instance, what if Demitri and some allies at the FBI actually kill him under medically controlled circumstances at exactly the flash forward time in order to uh, I'm not sure but there must be a good explanation! And then they bring him back to life. Or maybe there's a "zone" in which the flash forwards don't work, a sealed room somewhere where the conspirators control things, and Demitri happened to be in that room in the future, because he's figured out who the conspirators are, and has tracked them to their underground lair!
Although I can't explain away Olivia's smile.
She's being observed and their scheme hinges on someone thinking that Olivia is no longer loyal to her husband. Or she's whacked out on drugs. And Simcoe's shirt is off because they were having a barbecue and he got barbecue sauce all over it and it's in the washing machine.
*EDIT: waitaminute...that might be the explanation. Consider the shadowy guy on the security video in the stadium. He's not having a flashfoward, because he's awake during that time, so presumably the conspirators do have a way of shielding themselves from the flashforward - does that mean they take certain drugs or are in a certain location in the future? All it would take would be for Demitrit to be partially shielded - he still loses consciousness, but he doesn't see the flashforward.