Saying what was in Link's heart...wasn't something he was very good at. He was much better at doing, at finding ways to express himself through his actions.

So Shu will just see him look at his lanterns, silently. As he thinks about how much he misses those who are gone - and how much he wishes he remembered more of them. And then moves to carefully place each one into the river.

Afterwards though, he comes back to Shu. Looks at her. He's been thinking a lot about the people he's lost, but...she must have lost people too. Does she have a lantern?