Do you mean if they like someone else? If so, I would say, let's say for instance, if they had a crush on someone at work or school. They would probably every so often bring the person up hear or there. Maybe mention a joke they said or a funny encounter. It wouldn't be all the time, just every so often. If they like someone then that person is most likely on their mind a lot, so it is natural for them to bring up the person occasionally just to release the urge of wanting to talk about them. Trust me, us girls love to talk about the guys we like so to have to keep it all in is extremely difficult.