Thank you for your replies.

@sumowira Thank you for introducing me into ghosting. I have never experienced or heard about anything like this before. Yes, she was showing some "I mostly care about my self" traits.

@AzulOscuro: red flags? You know, before I met her, she told me few times that she was still experiencing wounds from the past, and that she was scared and have a hard time to trust. When I met her, I could feel that she was still a bit hurt inside. I somehow wanted to cover her with pure love, make her feel that this time it is going to be different for her, that she will not suffer, that I could heal her. I know that many people will say that it's a wrong thing to do, that the person has to heal on her own. And I understand the logic behind it. But both me and her, we had the same opinion, that love needs no reward, knows no fear, for love is enough. So I didn't really care if I get something back from her, I just loved. Nothing else. And I know, you can easily call me naive
I saw many red flags in the beginning, like her actions as I described above, but I thought that almost all of them (except for the connection thing), was some kind of defense mechanism based on her being hurt in the past. But I've experienced it before with other women before, that first 2 weeks they were kind of on/off, kind of careful, then they jumped into the relationship fully.
When everything went great later on, I haven't seen any more red flags. The last 2 weeks, I could see then again, when she suddenly become colder, and said that she can't come to me because she's scared of attachment (and hence my question to you), I could feel she might breakup soon. But as she came home from Asia, she was facing a hard situation at home, and not having any job, not knowing what to do and where to go, she was incredibly restless, turning in circles, I thought it was just too much of insecurity going on in her life, which was also affecting what she does with relationships . In our last conversation I suggested to her that I could stop contacting and writing to her, so she could have more space and being more on her own if that's what she wished... her answer was "Noooo, it would not be good for me. I am grateful that you listen. I have not so many people I can talk to right now. Come with me." Then she ghosted me days later.

When I look back, I can definitely see many red flags in the beginning and some in the end, but I regarded it as her having some issues inside her. With all the girls I have known, there were always some negative traits inside every one of them. We all have flaws. I didn't go carefully into the relationship, with looking at red flags to prevent being hurt. I never do it. That would be too much of thinking, that would be a cold calculation. I listened to my heart. That's what I always do.... for good or bad...