I personally saw this gesture, not only as an “I know”, but also Rarity being proud that Spike finally found the courage to tell her to her face. As was established, his crush on her was the worst kept secret, but he never said it to her face. Here? He did it and Rarity was happy he did.

@Background Pony  
People.

@Rotul7  
>Attacking lesbian shipping despite it not having anything to do with this  
>Thinking that affection=reciprocated romantic love  
>Using the “kids show” excuse despite the SA & Cadence relationship and the H&H Day episode

@Rotul7  
so much this, thank you.  
and i say that as a BIG fan of sparity.

@Rotul7  
they are close to cannon? that is dangerous, it could shot and kill them?

@Rotul7  
They do seem to enjoy the two interacting, and their relationship in the comics is pretty close. Gets pretty close on the show, too.

Sorry haters, but Sparity is ten times closer to cannon than any other lesbian spawning ship you have in your minds of fanfiction ideas.
 
Scenes like this, the comics, etc proves that Spike is getting some love. Hell even previous generation Spikes got their share of interaction.
 
It’s still a damn kids show, it’s only going to go so far. Pony and Dragon ages are ambiguous as fuck.

Yeah, that’s the thing: by leaving it ambiguous, the writers made us Sparity fans happy while not specifically outraging the anti-Sparity crowd. We can all agree that Rarity cares for Spike, but to what extent is an open question.

@Timberwolf  
You forgot the omega hybrid of them all.  

Keep it vague so you don’t step on any toes.

@The Twelfth Doctor Whoof  
We’ve seen hybrids so it’s clearly not outlawed!
 
Stop trying to block our fun!

Why did she not let Spike finish? I don’t think it was that big of a deal to stop him.
 
If she knew and appreciates it, she could still let him say the whole thing and still do the teary eyed expression.
 
If she knew and didn’t want to put him down, she could have still let him say the whole thing and… well, if she followed up with a teary eyed expression, it would’ve been really misleading. Its like she’s the one that gets hurt for rejecting him…

@lumpfish
 
There’s keeping a war going on and then there is being unwilling to admit what did happen.

@The Twelfth Doctor Whoof  
It’s good to see the war still continues on to this day.

@The Twelfth Doctor Whoof  
Yes. This. Whatever else, Rarity clearly appreciates and respects Spike as a person, and doesn’t want to hurt him.
 
Age might be a factor, but species, not so much . . . hybrids are canon, after all (griffins and minotaurs).

@lumpfish, @Background Pony  
The way I see it… Rarity’s clearly flattered that Spike’s finally willing to admit it directly. Her actions and expression say “I know, and thank you.” Anything more than that is left up to interpretation. She definitely likes him, but probably not in that way, due to his age and the fact that he’s a totally different species.

Hopefully no more of this pedophilia in season 4.

I figured she was just saying “I know.” The implications of that are up to everyone else to determine.

Aaaaaaaaaah I still remember the crazy fallout that came after this scene. The great war.
 
Two sides. One side saying it was Rarity telling Spike that she knew but to not tell her so she didn’t have to put him down, the other saying the same but she did it as an open-ended, possibly even romantic gesture.
 
I fought for the sparity side of course. Good times.

Now kiss.