[casinobonusese]

I'd be careful, it's likely the more you talk about it the more awkward it will be for the both of them and the more likely to interfere with practice. If the situation evolves and they end up having a thing for one another, then you can say "keep your feelings out of the dojo, while you're seeing each other and if you break up," although you probably already killed that by telling the girl he likes her. If the attraction remains one sided then it'll probably dissolve over time. I don't think it's any of our places to "forbid" feelings between people, even in the hallowed halls of the ultra traditional holy dojo.