Previews for The Big Bang Theory 9×15 suggest that someone has a secret in this year’s Valentine’s Day episode. Here are a few of our theories.

According to CBS, “The Valentino Submergence” focuses on the ups-and-downs of the gang’s relationships, and hints at unexpected developments.

“Sheldon and Amy host a live Valentine’s Day episode of Fun with Flags, Leonard and Penny grapple with getting older, Howard and Bernadette find a surprise in their hot tub and Raj is torn between Emily and the cute girl he met at the Comic Bookstore,” the network says.

But while the synopsis is curious, it’s the preview for The Big Bang Theory 9×15 — teasing “the biggest Big Bang secret ever” — that really makes us wonder what the series has in store.

Sheldon is going to propose to Amy

This would be a highly topical, and suitably significant development in Sheldon and Amy’s relationship — after all the subject was directly raised in “The Meemaw Materialization.” But would a proposal from Sheldon really be a surprise at this point? And is Sheldon really ready for that step? He did take care to mention that, after recently surrendering his virginity, he isn’t quite ready to pop the question just yet.

Raj is going to break up with Emily

We have to be honest — it seems pretty clear that Emily’s days as Raj’s girlfriend are severely numbered. After their near-breakup last season, The Big Bang Theory hasn’t bothered to show much positive interactions between them, and Raj’s recent attraction to Claire-from-the-comic-book-store suggests that he’s ready to move on from the redhead.

But unless this breakup is carried out in some kind of shocking way (which is not impossible, given Emily’s personality) we aren’t ready to call this a secret. And on a meta-level, we just don’t think CBS would tease a negative development like this for an episode billed for Valentine’s Day.

Somebody’s pregnant

Secret? Check. Surprising? Yes. Romance-related game-changer? Absolutely. This option ticks all of the boxes, in a big way. But who could it be?

For the first time in the show’s history, all three ladies of The Big Bang Theory could be pregnant in “The Valentino Submergence.” But since there’s probably only one bun in one oven, our bets are all on Bernadette. Penny has never been keen on having kids, Emily is probably on her way out of the show, and we’d have to call the trope police if Amy got pregnant after her long-awaited one night with Sheldon.

But Bernadette, who recently agreed to reconsider her decision not to be a mother, is the perfect candidate. We’re kind of terrified to see her and Howard as parents, but if you ask us, this choice is the clear winner. Get ready for tears: The Big Bang Theory 9×15 will be presenting the Wolowitz-Rostenkowskis with two pink lines on this Valentine’s Day.

What do you think ‘The Big Bang Theory’s’ big secret will be?