The change of subject is a dodge and Devero knows it, but he lets Yondu have it. He's not entitled to the other man's pain; he's not going to chase him for it if he's not ready to share.

Plus, he picked the right subject to dodge too. Devero listens to him gravely, his expression growing almost haunted as Yondu lays that out. He knows that Koumyou expects him to leave him someday, that's not news, but that Koumyou might consider that their happy ending? Oof.

It makes so much sense now that Yondu's said it, but it still makes his heart hurt. He actually has to look away to compose his expression, clasping his hands together and pressing them against his heart for a moment.

"Rust and ruin," he says quietly, sounding a little shooketh, as the kids say. "I... I think you're right. Oh, Koumyou."