Why would a female friend keep her party plans secret from me?

[Anonymous]

i was talking to this girl that i know yesterday at her work around 7 pm , mentioned what i was doing and that i might go downtown to a couple bars i sometimes go to but really nothing too exciting.

she didn't mention anything about what she was doing and i didn't ask either but i saw on social media today one of her girlfriend's ( not her page ) posted some pictures of a party they were at last night obviously as it would of been Friday.

i don't perhaps really care that she went to a small party with some girlfriend's Friday night just find it odd that she never mentions these parties to me , she's done this before and never says anything about them but i see pictures online of them so she's obviously been there.

not sure why she wouldn't be comfortable telling me as were friends that she was going to a party , she's keeping it secret from me

Updates

2 mo

i talked to her this week but she never mentioned the party or did i , also noticed that she showed up at gym in entirely different clothes than normal ( a belly revealing top ) so it seems like she's perhaps more wild at times than she is when she is around me

[Abbycado]

She doesn’t want you to know?

[Asker]

but why would it even matter if i know? just a small party on a Friday night and i had shared what i was doing or not doing , mentioned i had wanted to go out of town but gas way too much ( would of cost like $50-$60 dollars or more maybe just to drive to a nearby city )

[In_Trance]

Did you ask her why?

[Asker]

no as i just found out about the party today not when i saw her in person yesterday , she clearly has a secret party lifestyle thing going on

[In_Trance]

You should ask her why