Uncommited pledges.

[RockChalk]

If you had a friend who was always blowing you off to hang out with other people, would you still want to be their friend? No. There's nothing wrong with having a life outside of your GLO, but you should respect your sisters enough to be there when they need you.

It sounds like you already know for sure why she's been skipping. If you don't, definitely talk to her first. She could have a legit reason (having to work a lot, trouble at school) but if she doesn't, "see ya, wouldn't wanna be ya."