If a woman does not want to see a guy the best option get him to stop calling/texting is to tell him she is not interested. Ghosting as a first line of defense is ineffective. Many ladies are 'busy' and only respond when they are 'available' so mongers have learned sometimes they need to keep trying.
Based on other reviews YuYu IS one of those ladies, the fact that she is known to not respond and then suddenly respond encourages guys to keep trying (I'd give up after a few weeks, but still).
If after she directly tells a guy she is not interested if he continues to try to contact her, ghost, block, put him on a watch list whatever that's fair game. But until then he has no reason to assume he is doing anything wrong and she has no reason to assume he'll stop.