Why doesn't the 26-year-old boy agree to add an unfamiliar girl's QQ, to be friends with her, and to be familiar with her?
Because he thinks that all the girls he knows online are unreliable, he may see too many people who are often cheated online, but he is unwilling to accept strangers to add him to QQ. People like him are very cautious, preferring to stay alone rather than contact unfamiliar people to chat.