Is it normal for my bestfriend to ignore her date and flirt with other guys?

So last night was homecoming, and my bestfriend went with a guy who really liked her. He bought her ticket, brught her flowers, bought new clothes to match her dress, etc. Pretty much spent a shit load of moneyy. Andon our way to the dance, i told her that i hope someone dances with me. And then she told me i could dance with her date cause she didnt want to. Soi did, we were slow dancing and she got mad at me! And she just ignored her date the whole time and was grinding on other guys and stuff. I felt ao bad. Isthisnormal?