Sometimes I suddenly get quiet in the middle of chatting with a girl I like. What can I say to ease the embarrassment?

You have nothing to say, because you care about her too much, and everything is centered on her. Imagine that if this girl is just a friend, she should have a lot to say. I think it's inevitable that the atmosphere of chatting with the girl I like is awkward. You should relax yourself and be self-centered on the premise of learning to listen. Chatting with a girl, if you care too much about her, will often make her feel uncomfortable. So you should create a harmonious atmosphere and give others an impression that you are cheerful and lively.