Girlfriend broke up with me because I wrapped my legs around her/squeezed her. WTF?

She said I'm unable to annoy her, no matter how hard I try. I told her she's wrong, so we made a bet. I threw her to the floor and wrapped my legs around her like a green anaconda. She started to giggle and asked me: "is that all you've got?" I told her to get out of the scissor hold... she tried but failed. "Whatever, you'll get tired soon", she said. I just laughed at her. A few minutes later she told me to stop it. I just laughed and squeezed her with my legs. One hour later she was still wrapped between my legs. She was getting angry. It was very cute. She wanted to get out and all she had to was to admit defeat. She tried to bite me. She screamed at me and told me I was stupid. It was funny to see her squirm. She really lost control. 2 hours later I let her go. She was furious, punched me in the stomach, slapped me, then broke up with me. What the f***? She broke up with me because she lost the bet. Why is she so childish? What did I do wrong? I just tried to win the bet, so why is she so pissed at me? I really don't get it...
Girlfriend broke up with me because I wrapped my legs around her/squeezed her. WTF?
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