Search Results: really interested, just being nice

About a year ago, their was this cute girl I sat next to in geometry class. I helped her a lot with school; with homework, organization, studying, and especially geometry cause she's very bad at that kinda stuff. One day, in the middle of class she out of the blue tells me she really likes me. She asks me on a date to a school dance. I accept.
1-I show up to the dance. She already got A ride so I didn't take her, I assume it's one of her friends. Nope, her parents, this is fine until you realize the way I find this out is because her parents are at a table sitting with her. I'm like 'this is fine, Ile meet her parents! Cool right?'. I talk to them and find that they're really cool! I talk to them about my interests and theirs. Then they leave to go home.
Ok, so my first question- Is this normal? To have your parents come to a dance like this? I'm not angry, just confused, cause I would be so embarrassed if my parents came, but she seemed to think it was ok.
2-After that, I go to where some food is being served and bring her what she wants and we eat a little. But she is dead quiet. Responding in one word answers n' stuff. In general being cold. I ask her to dance and she declines. She then leaves to go to the bathroom with her friend. She comes back and I ask again, she declines, I try to talk and I get more one word answers. She gets up again and goes back to the bathroom with her friend. This continues for the next 3 hours until the dance ends. After I help clean up her parents show up and I walk her out. I get in my car and leave.
My main question-I later ask one of my romantically intelligent friends what happened, he told me I was too friendly to her parents. Can you be too nice to a girl's parents? I know that If a girl was nice to my parents ide be Happy. Here's some context-> she hates her parents.
Also, do y'all think it's ok to invite someone to a dance and not dance with them?
If y'all are curious, we haven't spoken since.
What do y'all think?