I don't think it needed to be said - this is Tidus' story, and we, as well as the rest of the party, are aware of his feelings towards Yuna from the begining. The question was whether or not Yuna returned those feelings. Her final confession to him of, "I love you," was her admitting that she did, indeed, return those feelings. Tidus didn't need to reconfirm he still liked her - it would have wrecked the moment.