If she is always really serious around you, she might not like you. It could just mean she is shy or not a humorous person, but often girls joke around with guys they like. If she genuinely seems like she is having fun with you – teasing you, joking around with you, and laughing at your jokes – she might like you. If your conversations consist only of basic day-to-day small talk (“How was your weekend?” or “It is really warm out today.”), she might not like you. Although it could also mean she is too nervous to ask you anything deeper.  If she is asking you about your life and interests and telling you about hers, she might be interested in you. If she has never brought him up or only says negative things about him, her feelings for him could be fading. If she goes on and on to you about how perfect he is, she probably does not like you. It can be complicated though because it is possible to have feelings for more than one person. If she says, “Tanner bought me roses yesterday and we are going out to dinner tonight! He is the best boyfriend,” she probably does not like you. If she says things like “Tanner and I got in a huge fight last night because we never do anything together,” her heart might not be all in the relationship. If she goes out of her way to talk to you and give you attention, she might like you. Is she speeding up to catch up with you and talk to you or does she only talk to you if you happen to be near each other? If she seems to be going out of her way to talk to you and show you attention, she might like you. Pay attention to your online conversations, not just the conversations you have in person. If she never sends you texts or snapchats, she might not like you. (Although she might not be doing this because she has a boyfriend.) If she always sends you texts or snapchats about her day-to-day activities or asks you about yourself, she might be interested. If she only texts you once a month to ask about school or work, maybe not.

TL;DR in Vietnamese:
Đánh giá tính cách hài hước của cô ấy. Suy nghĩ đến chuyện mà cô ấy nói với bạn. Chú tâm khi cô ấy kể về bạn trai. Để ý thời điểm cô ấy nói chuyện với bạn. Đánh giá tin nhắn.