Why didn't they mention this around me?

[Axalon]

The girl I like went to the school dance with her friends recently. I am older than her and we both go to different schools, so there is no way I could’ve asked her to go with me. The only reason I know about this is because I overheard her mom to her dad about it. She said that she waited to tell him about it when I wasn’t around. Her and her mom left without saying a word to me and they didn’t tell my dad about it when they got back. Normally, her mom tells my parents what’s going on in her and her kids lives. Why did they feel the need to keep this from me? It’s not like she was going with another guy. I would’ve asked her myself, but we go to different schools and that is not allowed.