Well, that was a smooth move from Uda. Wait until Riri gets properly rejected so there's no conflict, confess right after while her interest in love is still high and before she finds someone else, then goes away to leave Riri time to sort her feelings and unexpected confession.
For something that is very far from the usual fated love confession, it was handled in a satisfyingly way, I must say. In fact, the way Uda handled the whole one-sided (so far) crush was something I quite liked.