[The small praise just sets her smiling more with a simple nod. While she's been away from Marina for some time, it's plain to see that he cares about Yuuri. And Yuuki isn't surprised. Yuuri's incredibly easy to get along with. What's more, Nico, while he seems a little... shy, maybe, is actually a very sweet kid, too.
She's glad that they became such good friends. They probably balance each other out.]
It's okay. It's natural to worry about the people you care about, right?