I am sure it's not a glitch in the software or something like that. What does it mean when someone keeps typing, then stopping, then typing again, but never actually sends what they were typing? What am I supposed to think and how should I react? Do I pretend that I don't notice? This specifically happens on Whatsapp when I'm (obviously) online, so the other person really has no way of knowing if I've actually seen what they're doing. Seriously confused here :/

Note: They are the opposite gender of me and I've known them for about a month (although I'm not sure if that's relevant or not).