Who else caught this?

  
When Gary and Pawbert help Judy in the collapsing lodge, Gary refers to Nick as Judy's "partner."

  
"They already have your partner. They can't get you, too."

  
At this point, Gary doesn't know much about Nick and Judy. The biggest thing he knows about them is that they're partners on the force. He doesn't realize the depth of their relationship and that it goes beyond mere police partnership.

  
In Pawbert's tent, he refers to Nick as Judy's "partner" once again.

  
"...then, we'll fix things for your partner, too."

  
I believe at this point, it's sinking in for Gary how much Nick means to Judy and that he's much more than just a simple police partner to her when he sees how heartbroken she becomes at the mention of him.

  
Most likely, he's thinking "Wow. He's not just your partner. There's obviously something special between you two."

  
I believe it finally fully sinks in for Gary how much Nick means to Judy when he sees her, immobilized and dying from venom, prioritizing Nick over herself. She needs medical attention right away, yet her primary concern is not even herself; it's saving her best friend. Notice how Judy is most heartbroken when the fear of losing Nick is seemingly about to come true. Gary can see this, and it leads to this simple but powerful quote.

  
"We're gonna save you, and save your friend."

  
For the first time, Gary refers to Nick as Judy's friend. And notice how when Gary says Judy is going to get saved, she doesn't smile. But the second he says Nick is going to get saved, Judy expresses the faintest smile (as seen in the 2nd screen shot). That's the confirmation Gary needs. Even as Judy is on the verge of death, the only thing she cares about at this point is that Nick is safe. Gary can see this. He can finally see that Nick is way more than just a partner to Judy. 

  
It's subtle, but it's yet another powerful example of just how deep the bond is between Nick and Judy.

A Subtle But Powerful Change In Gary's Choice Of Words