My sister busy 7/24?

I do not know why i dont see her online. I haven't talk to for a three weeks now. I am worried and thinking about her. Is possible she is busy 7/24? My husband is working hard. But he still have a free time. But when I ask my sister about it. She said she's busy! I do not understand why she doesnt have free time. Is she telling the truth? or not?