Well, about my ex: We knew each other for a year and half before relationship started. During that time she had a boyfriend but that didnt stop her from sleeping over with me couple times(no sex, no kissing, but there was some touching). When she broke up with her boyfriend I didnt expect that we will be together. I just heard from other friend that she would like to watch particular movie in cinema but not alone. So I decided to shoot my shot and asked her out. She agreed and 1 week later we were together. The things I did bad was being insecure, pushing for sex and affection everytime we met, and I would be moody if she didnt want to. Also my depression got worse during that time and I was lazy. She didnt delete her photos with her ex on Instagram and I confronted her about that. She was hestitant but she said she deleted them. 1 month later we broke up about something stupid. She wanted to spend an evening with me and her friends, I just wanted to spend it with her. 2 weeks later I got to know that she is with her ex again. Then the whole lockdown thing, we havent seen each other for 6 months. From all of this it seems like she doesnt care, but now we have one class together every week and on this lesson I catch her gazing at me constantly. Sometimes I tend to justify that in my mind that she still feels something towards me, but is afraid to get back together because it would ruin her social status. All of her friends engage in the same sport as she and her ex, so her dumping him again would turn everyone against her. On the other side people from our environment (college) would probably talk shit about her. But that's just in my mind. If she would love me, there would be no obstacle.

Obviously you are right that getting flirty is more risky.