"But I can't afford to rescue Tina," said Newt. "I've already spent so much time getting Credence back, and we can't afford to delay going to Crete any longer."
"That's a good point," said Bunty a little too happily. "If all the fantastic beasts died because you took the time to rescue Tina, you'd never be able to forgive yourself."
Newt shuddered at the thought of a world without dragons, hippogriffs, or even puffskeins. That could not be the price of rescuing Tina! It could not! He would not even risk that happening! And yet... and yet...
"What if Tina dies?" he asked. "I realize that next to all the fantastic beasts in the world, the life of one single person shouldn't matter, but... but... I can't..."
"Hey, I have a solution to this problem," Credence chimed in. "You don't need to worry about Tina dying. Grindelwald won't kill her because he's actually good." By the way, it turns out Credence has a gay crush on Grindelwald but is afraid to admit it because Ma Barebone raised him on homophobic propaganda. This is canon now.
"All right, I've made my decision," said Newt with a heavy heart. "We're going to Crete now."
"No, dear brother, you must rescue Tina," said a heroic voice heroically. And then, Theseus randomly stepped into the room!