Questions: Girl's Behavior

She is an office mate, and I have to add that she is a fat girl, and I am saying this, because people think that this may have relation.
When I started meeting her in the office; and I began to be interested in her, she became "crazy" because I was interested in her. I also saw her, because she was constantly looking for me, she would come in an hour before to see me, etc. She began to tell me to meet, and like "whenever you want", "wherever you want", "I'm going to look for you" with a lot of desire. Soon we met, we went to dinner and then we spent the night together; I interpreted that it went very well; In fact she don’t wanted to leave, she wanted to stay with me, but I had to work. Until there everything seemed perfect. In fact, in a later discussion, she told me that she had a great time when we met and she was delighted. The thing is that we kept talking all day, she worried about me. Let's see, everything was fine, but when it was time to meet again, she didn't say no but we didn't meet; It was like she was scared or something.
Like this for months, and when I was tough and told her to stop talking few days later she was looking for an excuse to talk to me again. When talking about the subject it was impossible to get anything out of her, that she does think I'm very hot, that she likes me and such.
A week ago I left for another job and asked her more thoroughly. She told me after insisting again after many months, that she was comfortable with me but that she knew that for a night of sex she was not going to be the woman of my life. That she didn't expect me to want anything more than that with her and that it scared her. I asked her several times about the fear of a relationship with me and she didn't answer any, she just insisted over and over again that she didn't want to lose contact. Several people have told me that they didn't expect me to notice her and we don't hit as a couple, due to her physique. Because we talked and even so she complimented me.

I get to know a girl one night. Great conversation. Get her Instagram. I message her. I either get ignored or receive dead messages back

Then she just stalks all my insta stories

I don’t understand women.