why girls say they are busy online on facebook?

[LonestarG]

So i dated this girl once, and i think there was a good connection, then same day i texted her on facebook to see if she got home safe and yes she answered, then next day i asked how is she doing she responded, but after two days i texted her on facebook asking what she is doing she said she is busy, shall i continue texting or stop? i just have her on facebook and she still is not comfortable to give out the phone,