Search Results: no response to phone calls

Long story short this girl I work with approached me one day and was very flirty with me. We have mutual friends but we never spoke so I didn't think she knew who I was. Eventually we exchanged numbers and began talking all the time. At first I thought she just wanted to be friends but after a while it became very apparent that she wanted more. She would constantly ask me to hang out and if I couldn't she would get upset about it. If I didn't answer her phone calls she would be upset about it and her first response was always are you with another girl which I would always reply no even thought we weren't anything at the time just friends. Eventually we started hooking up and we became very attached to each other talking all the time telling each other how we feel about each other and always having so much fun when we were around together. She would always drop hints how we would be such a cute couple and that we look good together. Eventually down the line I find out on my own without her telling me that she has a boyfriend. When I questioned her she admitted to it and said that he goes away to school and she doesn't know what he does up there so he could be cheating. She told me how she started to like and me she didn't know what to do cause he was away at school. I told her while I would not blow up Her spot to anyone it was messed up and we should go back to being friends. Although she was hesitant at first she agreed and we went back to being friends. It was never the same though we didn't talk like we used to and we grew further and further apart. Every once in a while she would say how she missed me and wanted to back but to being good friends but when I would try she would give me the cold shoulder. Fast forward to now she ignores me and is very cold towards me while very sweet and nice still to all of our mutual friends. I don't know what I did wrong and am very confused as to why she hates me so much should i just ignore her or try and fix our friendship

I was trading responses with @vladikre on a question about when do you make contact after a first date that went well (unlike the date in the cartoon.) https://www.girlsaskguys.com/dating/q2395706-after-a-great-first-date-how-soon-do-you-want-to-hear-from-him-or He responded, "I usually wait for a week, where the girl grows interest. I never suggest telling her you had a nice time, cause it's shown when you actually go on a date with her. be mysterious. they grow interest. after a week or so you call her again to arrange another date. nothing else. no blah blah, no sweetness. phones are to arrange, social media too."

He thinks that calling later that same night is "clinginess, self assurance and neediness." I suggested that what he recommends is called playing games and that most people want you to drop pretenses and be honest and candid about your feelings and your intentions. But I am older and perhaps out of touch with contemporary thinking on that subject, so. . .

Do you think waiting to call 5 days after a first date to create anticipation and desire is a smart move or is it just game playing?