I wish people communicated more directly nowadays. Text messages are convenient, but they do not substitute real communication. Sometimes someone reading a text but not responding will cause anxiety in doubts when really the person got interrupted. If it's a pattern, that tells you something else though. If someone regularly just reads your text, but does not respond in a timely fashion, I think it's time to move on.

Maybe they'll get back to you eventually, but don't put your life on hold for the person. There are people who will show more interest and show consistent patterns of communication, so it's not worth focusing on the ones who play games or simply do not invest enough in getting to know you or ready for a relationship.