... thoughtlessly, she grabs hold of the ring on her finger. This isn't all that unusual for her-- you've witnessed her remove jewelry prior to having sex before. For Brooke, this is just muscle memory momentarily taking hold of her. In this case, however, you remember the words of the old woman who gave you the watch and the rings in the first place, who warned you both very specifically not to remove them in any other time but the present. You don't know exactly what the consequences will be, but the second you see Brooke begin to take off the ring, you know something bad is about to happen. "No, wait, Brooke! Don't remove your ring!" you call out. But it's too late to have any impact. The ring slides off of Brooke's finger.
At once, you begin to understand why you had been warned to keep the time travel items on. As Brooke lets go of the ring, it vanishes into thin air, and she instantly freezes in place like a statue, still stark naked. "Brooke?" you cry out. "Brooke?!" You lay a hand on her bare shoulder, hoping perhaps to jostle her awake. But it's no good-- without the ring on her finger linking her to the time traveling abilities of the watch, she is just as motionless now as everything else around you, waiting for you to restart time again. You're left now with a dilemma-- you can't just keep her frozen like this. You're going to have to push the button to unpause the world eventually. But now that her ring is gone, you aren't quite sure what's going to happen when you do. For all you know, maybe Brooke's presence in the past without her ring could create an anomaly, and the fabric of spacetime could be torn apart, or something else like that out of a sci-fi movie could happen. You wonder what happened to the ring.
And then it hits you. The rings were designed specifically to transport whoever wears them through time. The set that you received contained TWO rings-- yet, only the one that Brooke had been wearing was brought into the past. The other stayed behind, back in 2015. You deduce that the rings only work when worn. Therefore, the moment Brooke's ring left her finger, it must have returned to the present. You consider briefly going back to the present to look for it, but you quickly realize this too is problematic. Brooke can no longer go back with you to the present. If you leave Brooke here, nude, in your parents' bedroom, not only would it be terribly humiliating for her, but it could have unseen repercussions on the present. Besides, even if you could go back, find the ring, and bring it with you on your finger-- how would you be able to put it on her without it disappearing again?
You look over your girlfriend again-- little more right now than a nude statue made of soft flesh rather than stone. And you're still naked too. A devious idea briefly flashes across your mind.