Article in English: Guys who are using a woman for sex often give few or no details about themselves. Have you gleaned what you know about him from friends, personal observation, general conversations, past interactions, or has he really volunteered personal and revelatory information about himself to you? This is a VERY telling point, so it is worth considering carefully. Does he get bored quickly when you discuss your work, your hobbies, your activities, general daily issues? Does he try to stop the discussion and turn it back into "fixing everything with a snuggle on the couch"?. If so, he might be pushing aside the emotional entanglement of a real relationship just so that he can keep open the using side without feelings of guilt. He could also present himself as a counselor and offer advice about all of your issues, but not disclose any of his so that you can be involved in his life. Have you never heard him randomly ask if you're upset, ask how your day was, or just wonder why you had tears in your eyes? If he seems absolutely allergic to your emotions, then chances are it's not because he's too shy to ask or too awkward to help you deal, but it's because, well, he just doesn't really care that much. If he's just into you for sex, then any of your complicated, messy feelings will be a hurdle for him and nothing more. This may seem like a no-brainer, but many women refuse to see what's right in front of their eyes, even if they hear it. If he has told you that he's just into casual dating, that he doesn't have time for anything serious, or that he's just not a relationship kind of guy, then he probably meant it. You might have brushed this aside, thought he was just trying to play hard to get, or were convinced that you could change him. Well, if he has specifically told you that he's essentially not interested in much more than sex, then you need to rethink your "relationship." Have you been hooking up for months and haven't ever talked about what you're going to do even a month from the day you see your guy, let alone...

Summary in Vietnamese:
Anh ấy không bao giờ tiết lộ thông tin cá nhân. Anh ấy có tỏ ra nhàm chán khi bạn nói về bản thân? Dường như anh ấy hiếm khi quan tâm đến cảm xúc của bạn? Anh ấy có nói rằng không muốn một mối quan hệ? Anh ấy không bao giờ nói về tương lai với bạn? Có phải tất cả nhưng gì anh ấy nói đều về tình dục?